New York’s Democratic nominee for attorney general prevailed in a hotly contested primary this September in a way candidates aren’t supposed to these days: by running to the left of his rivals. Under the banner of "economic fairness, social justice and real reform"—and reminding voters that he wrote last year’s legislation undoing New York’s wildly punitive Rockefeller drug laws—State Senator Eric Schneiderman edged out Kathleen Rice, a former homicide prosecutor.

Schneiderman won with a surge of votes in his native New York City, where at lunchtime on primary day he made his way to downtown Brooklyn, flanked by a pack of elected officials and volunteers. From Governor David Paterson and Congresswoman Yvette Clark to the young City Council aides handing out fliers, Schneiderman’s campaigners had one thing in common: an affiliation with the Working Families Party, the most influential progressive force in the state.

Schneiderman came into office in 1998, the year the Working Families Party first secured a spot on New York ballots. Since then, the party has put progressive candidates in office and given the state legislature its first Democratic majority in generations through aggressive outreach to voters—and an unusual feature of New York elections. Under "fusion" voting, candidates in a general election can run as the nominee of more than one party, upending the usual dynamic of third-party politics that curses minor-party candidates with the Nader effect, in which a vote on their party line denies it to a major party nominee. In fusion states, third parties "cross-endorse" major-party candidates so that every vote counts. By tallying voters on their own ballot line, third parties influence turnout—and the agendas of the candidates they support.

Under normal circumstances, Schneiderman, an important Working Families Party ally, would have been a shoo-in for the party’s early endorsement. But unlike in every other election he’s run in, Schneiderman was not the party’s nominee on primary day this year, and his campaigners took great pains to note that they were not there at the party’s behest.

The shadow hanging over the race, and the Working Families Party itself, was cast by the current attorney general, Andrew Cuomo. In order to maintain its ballot line, the party needs to win at least 50,000 votes in the governor’s race in November. To survive, it has hitched itself to Cuomo as its nominee.

In exchange for his support, Cuomo demanded that the Working Families Party hold off on endorsements for governor and attorney general until after the September primary. He then insisted that the party sign on to his entire policy agenda, which includes a property tax cap, a freeze on state budgets and worker pay, and a reversal of one of the party’s signature successes—a tax hike on households earning more than $250,000 a year.

Cuomo was emboldened by a loose coalition of conservatives and business leaders deeply opposed to the Working Families agenda and threatened by the elevation of labor unions and progressive allies to such heights of influence. Opponents have mounted increasingly vicious attacks seeking to maim—or kill—the party. A federal investigation, subsequently withdrawn, and a lawsuit alleging campaign finance violations in the party’s canvassing operation forced the party to divert funds and energy to the cause of defending its existence.

The voice of opponents has been amplified by hostile media. The editorial page of the Daily News called the possibility of the party’s demise a "pleasing prospect"—pleasing, certainly, to owner and Boston Properties CEO Mortimer Zuckerman, whose nemesis is building workers local 32BJ, a major player in the Working Families Party. The Rupert Murdoch–owned New York Post called Working Families a "squidlike party" "expert at growing tentacles to stay one step ahead of the law" and "a clearinghouse through which elected officials are bought and sold by New York’s public-employee unions." The Post repeatedly called on Cuomo to renounce the party’s "corrupt" ballot line.

As such, the party came to Cuomo with a weak hand. Although the lawsuit and investigation proved frivolous, defending itself against the charges had drained the party’s resources. Running its own third-party candidate would have come at too high a cost. Instead, as Dan Cantor, the party’s executive director, explained in a statement announcing the Cuomo endorsement, "We will be fighting for his electoral victory in November and then fight for legislative passage of his New NY Agenda in January," adding that the executive committee "unanimously" agreed to this decision.

Cuomo’s downsize-government agenda was a bitter pill for the Working Families Party to swallow. Now that Cuomo is carrying the party line, leaders have to convince constituents that the party is not an accomplice to a rush to the right for New York. Once in office, he will be under constant pressure from the right to keep Working Families in line. The political action committee New Yorkers for Growth, led by state GOP chief Ed Cox, responded to the Working Families endorsement with a Shepard Fairey–style mash-up depicting Cuomo as Che Guevara. The big money in New York State politics—from real estate and Wall Street—is backing Cuomo against Tea Partyer Carl Paladino and expects to be taken care of in return.

In order to get Cuomo on board again in 2014, Working Families will have to spend the next four years showing deference—at least publicly—on issues it once would have pushed aggressively from the left. The party that just this spring declared it would support only those candidates who pledge to tax Wall Street bonuses will have to soften one of the main planks of its agenda—the pursuit of economic justice—in a state that is home to some of the nation’s wealthiest people and a large concentration of its poorest.

Which raises the question: why have a progressive party if it isn’t free to be, well, progressive? "It’s hard not to compromise your principles," observes a consultant close to the party. "The history of the party is one of expedient political decisions along the way for institutional reasons. It’s understandable, but how much is too much? At what point have you lost your way?"

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The answer to these questions has implications far beyond New York’s borders. In November voters in six fusion states—Connecticut, Oregon, Delaware, South Carolina and Vermont, in addition to New York—will have the opportunity to vote for Working Families candidates in state and federal elections. In Connecticut Dan Malloy is running for governor as a Working Families candidate, as is Senate candidate Richard Blumenthal—both could receive a crucial edge in tight races against Republican opponents. Although the party doesn’t yet have the critical mass outside New York to move legislation—it just got on the ballot in Oregon and Connecticut in 2008—it is already using its canvasses and campaigns to bring urgent proposals into the mix, including the creation of a state bank in Oregon that would handle taxpayers’ money in a public trust. A bill that would mandate paid sick days for workers has come close to passing in Connecticut, provoking sharp attacks from employer lobbyists.

The party’s influence remains most pronounced in New York, where it not only elects statewide candidates but has filled the seats of state and local legislatures with progressive, party-endorsed candidates. One of them is Gustavo Rivera, who scored a historic upset against an entrenched and corrupt incumbent to win the Democratic nomination for a Bronx State Senate seat. Rivera won with the help of volunteers like Patrick Cousins, a member of Stagehands Local 52, who decided to take three weeks off to volunteer for Rivera and Schneiderman.

"Phone-banking, handing out tons of literature, standing by the subway station every day, watching the polls today at 5 am," Cousins recounts the nonstop activity. "My kids are grown, so now it’s time to give back." In the Bronx, unknown Rivera took nearly two-thirds of the vote, trouncing State Senator Pedro Espada, who helped stage a 2008 coup that briefly brought Republicans back to power in Albany. Working Families canvassers had knocked three and even four times on every Democrat’s door in the district that they could. While Espada handed out school supplies to court voters, Working Families canvassers appealed to voters’ hunger for values and results.

"What issues are important to you?" canvasser Mike Staab asks 92-year-old Mildred Kaminsky, a resident of the union-built Amalgamated co-ops. "Jobs," she replies, as her home health aide looks on. "I couldn’t agree more," continues Staab, a recent NYU graduate. "Gustavo Rivera wants to make sure that jobs pay a fair wage."

This isn’t just talk. Assuming he wins in November, Rivera will become part of a progressive Democratic coalition in the once impassably Republican State Senate. That bloc has passed formerly unimaginable measures, including a minimum-wage hike, a bill of rights for nannies and housekeepers, a moratorium on destructive natural gas drilling and a cap-and-trade fund devoted to creating well-compensated green jobs.

In these battles, the Working Families Party has proved adept at exploiting division and instability as openings to push progressive legislation, and at out-thinking and out-organizing its opponents. One winning bill created a green jobs fund that will weatherize homes statewide. A second provides for utility-bill payment for energy efficiency retrofits. Both stemmed from the work of the Center for Working Families, an independent research group that was founded by the Working Families Party. Operating in the mold of ALEC, the conservative state legislation machine, the center provided extensive supporting research and legislative development for the green bills, and continues to help shape the programs.

The Domestic Workers Bill of Rights, which establishes a standard workweek and rights to paid overtime, grew out of a long-running campaign from Domestic Workers United, a tiny New York City group founded by nannies and housekeepers tired of mistreatment. The Working Families Party often teams up with other advocacy groups for legislative campaigns, to mutual benefit. "We were novices, and we’ve learned a lot from them about how Albany works," says Domestic Workers executive director Priscilla Gonzalez. In the end, Working Families and the domestic workers could only push the legislature so far. None of the economic benefits in the original bill—including paid sick days, holidays and vacation—made their way into the final version. Nonetheless, on a small scale, the workers experienced the party’s larger challenge as it strives to advance a broadly balanced economy through means like progressive taxation, strong social programs, tenant laws and wage standards.

To see continued success, the party will have to add more loyal partners like Rivera, who help the party build influence and momentum. The New York Working Families ballot line, currently row E, induces candidates to support an agenda in line with that of the labor unions and progressive groups that lead the party. Running on the line signals to liberal voters that a candidate is committed to their values and issues. "They are the Good Housekeeping Seal of Approval for progressive Democrats, and they’ve earned that," says New York City public advocate Bill de Blasio, who won his seat—and with it a shot at the mayor’s office—with the help of the party’s skilled and disciplined canvassing operation. He was part of a push last year that brought the number of Working Families–nominated candidates on the City Council to a record thirty-six out of fifty-one seats, as well as the comptroller’s office.

The stunning success of Working Families Party–endorsed candidates in last year’s New York City primary elections took even party leaders by surprise. "In retrospect, if you have good candidates and good ideas and a hard-working campaign, that’s a pretty good combination. We had superior campaigns with superior programs, and that’s a winning formula," says Cantor. In legislatures, he sees a unique power to put government to work in the public interest. "Nearly everything progressive in New York City and State began as a legislative initiative. They’re closer to the base, more accessible, more accountable."

Although the New York City Council has long leaned liberal, the state legislature, which includes heavily Republican districts upstate and on Long Island, has, until now, been a very different story. More than simply filling seats in the State Capitol with its allies, the Working Families Party has measurably transformed how Albany understands New York’s balance of power. For years, state leaders have pitted upstate interests against those of the city—for example, feeding small towns’ prison economies with drug war inmates from the Bronx and Brooklyn. Instead, Working Families is advancing economic justice wrapped in a vision of shared destiny that unites Manhattan—home to the nation’s highest income inequality—with withering upstate. To obtain a Working Families Party endorsement for state races this year, candidates had to respond to a sixty-five-item questionnaire and support the Working Families proposal to tax Wall Street bonuses and million-dollar-plus earners.

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The success built on such uncompromising demands has brought an inevitable backlash. The wave of attacks bring uncomfortable echoes of last year’s war on ACORN. In fact, we’re watching a sequel. ACORN was a Working Families Party founder, and its organizing tactics have driven the party’s success. Both groups embrace strategic grassroots advocacy on behalf of poor people and immigrants, and focus on electoral empowerment to move progressive policy. Remember that it was ACORN’s voter registration drives, targeted at disenfranchised black and Latino citizens in red states, that put the group on conservatives’ hit lists. "When you are opposing corporate America, big business, big politics, big moneyed interests and a lot of special interests, you will be attacked," says ACORN CEO Bertha Lewis, a longtime Working Families Party leader.

The alliance between ACORN organizers and the Working Families Party helped secure the party’s impressive victories in Albany, starting with a 2005 minimum-wage hike. ACORN turned out its members for rallies that put the heat on state legislators, who had to answer to crowds chanting "$5.15 is not enough." But by early 2009 the anti-ACORN attack machine had zeroed in on the Working Families Party. "Media coverage of ACORN and that organization’s illegal activities in New York, California and elsewhere has largely ignored one of ACORN’s most successful projects; New York’s Working Families Party," Republican strategist Roger Stone wrote on Andrew Breitbart’s Big Government website. Working Families, Stone asserted, is a "criminal enterprise" and a "wholly owned subsidiary of ACORN."

Along with those lies, Stone dropped a clue to the real root of the backlash: "Since the major parties no longer have the man power to organize an effective voter canvas [sic], Democrats have turned to the WFP for their door to door campaign activities."

Working Families’ power over the Democratic Party is exactly what scares New York’s business elite—that the Democrats, once reliably centrist and business-friendly on taxes and social policy, now answer only to their left-wing opposition. "There’s no question that both the Democratic and Republican parties of New York have ceded their position of pre-eminence to the Working Families Party," says Kathryn Wylde, CEO of Partnership for New York City, an association of business leaders. "Neither Democrats nor Republicans have had control over policy that the Working Families Party has had by being focused, persistent, communicating effectively about who they are and what they stand for. As a result, a relative fringe element is controlling a big part of the political and policy dialogue."

New York’s real estate industry is particularly vulnerable. The party backs stronger rent regulations, and with affiliated unions it has advocated living-wage standards for real estate projects receiving government subsidies. Last year members of the Real Estate Board of New York poured nearly $700,000 into the rival Independence Party—Mayor Michael Bloomberg’s vehicle for snaring liberal voters when he ran as a Republican—to bankroll opponents to Working Families City Council candidates. All the Independence Party candidates lost.

The Independence money was no match for the Working Families Party’s canvassing operation, which compiles lists of likely voters and sends campaign workers to their doorsteps to promote issues and candidates. Run via a company called Data and Field Services, the canvass is both the party’s most powerful tool and its deepest vulnerability. As the Independence-backed electoral campaigns fell flat, opponents moved to attack the source of their defeat, and—following the anti-ACORN playbook—whip up a scent of scandal around the party’s activities.

Last year, a series of articles in a local political newspaper suggested that Working Families might be undercharging Data and Field Services—in effect, circumventing New York City campaign finance rules that limit spending by candidates receiving public funds. Soon, the party faced a lawsuit and a federal probe into its finances.

Just before election day, Randy Mastro, a former deputy mayor to Rudolph Giuliani, filed suit in Staten Island on behalf of Republican Party loyalists, charging Data and Field Services with violating election laws. The lawsuit promised it would reveal "an audacious scheme to violate the law by using corporate subterfuge to hijack our local election process."

Nothing like that came to light, and it didn’t have to—the intended damage was done. Data and Field Services owes more than $400,000 in legal bills—funds that will have to be squeezed out of billings to Working Families Party and its candidates. The party, meanwhile, still owes more than $100,000 for a report it commissioned from New York State’s former chief judge, recommending management reforms.

Money is flowing out much faster than it is coming in. In the first six months of 2010, the Working Families Party spent about $380,000, nearly 40 percent of its expense budget, hiring Data and Field Services canvassers to engage voters on issues like election reform and the bank bailout, and to collect tiny donations. In sums of $5 and $35, they raised less than $250,000. Meanwhile, labor unions—the party’s core source of funding—are seeing losses of members and dues payments in the economic downturn. The Center for Working Families has had to move to separate offices and cannot share administrative resources with the party.

Other states’ Working Families Party organizations have taken the woes of New York’s operation as a cautionary lesson but also, perversely, as inspiration. "There’s only so long powerful interests will let you build power before fighting back," says Steve Hughes, state director (and the entire paid staff) for Oregon’s Working Families Party, which is fielding its first candidates on a fusion ballot this year. "We’re not used to having success in our camp. This is the kind of stuff that happens when you’re successful."

In New York, the party must look ahead to a fresh, Cuomo-friendly way to advance its vision, which Cantor boils down to this: "We can actually use government power to improve people’s lives. The right believes that’s not possible, but they’re wrong—we’re right." On the state level, that means pressing legislators and agencies to invest in everything from energy-efficiency retrofits to public transportation, not only to create good jobs but to lower the cost of living and raise the quality of life for everyone.

The New York party has also begun to exercise influence in Washington. Earlier this year, it teamed up with its counterparts in other states and with to press Congressional delegations to advance aggressive campaign finance reform in the wake of the Citizens United decision.

The party’s growing role on the national stage means that the attacks against it from conservatives are hardly over and that the worst is likely yet to come.

"What we have learned in the last year and a half is that when you infringe even in the slightest fashion on the power and prerogatives of the corporate elite, they react very, very strongly," says Bob Master, a party founder and co-chair (in his day job, a political director for the Communications Workers of America). "The party emerged over the past several years as a real voice for equality and proconsumer regulation and curbing corporate excess. A number of oxen were gored. And we’ve got some pretty angry oxen on our hands."