If Democrats take back control of the House of Representatives next month, they could become the dynamic wedge that starts to revitalize national politics. How? By legislating aggressively on ignored issues that people care about. By opening up the frank debate Republican leaders have suppressed for the last decade. By dragging reluctant Democratic senators and presidential candidates toward embracing a more progressive agenda for 2008.

That is not a prediction, because “if” remains the operative unknown. But the ingredients are present for a much bigger deal than conventional wisdom in Washington assumes. The Wall Street Journal editorial page recognizes the threat to conservative hegemony. While George W. Bush would still be President and armed with the veto, the Journal warned, “the national debate would nonetheless shift notably left.”

If Representative Nancy Pelosi, the Democratic minority leader, becomes Speaker of the House, that is a big deal in itself. She will have reached the highest position of power (third in the line of presidential succession) ever achieved by a woman. The right demonizes her and the media occasionally make light of her skills, but Pelosi is stronger and tougher than her reputation. “Anybody who’s ever dealt with me knows not to mess with me,” Pelosi told Time magazine. She has consolidated her power where it counts, within the Democratic caucus.

Even if Republicans hold on to the Senate, a House majority for Democrats will gain voice and leverage, plus the clear power to block what remains of Bush’s right-wing agenda: tearing up Medicare or repealing the estate tax and other tax relief for capital. The Democratic House caucus would be freed to set its own agenda and act on it. That dynamic will change the national conversation in the run-up to the next presidential election.

If this happens, expect a flurry of long-stalled but popular legislation to be passed promptly in the House, with likely votes from nervous Republican moderates. Freewheeling debate will be revived. The interplay between House and Senate will suddenly require compromises with liberal Democrats instead of the lockstep conformity imposed by the Bush White House.

Similar circumstances arose three times during the twentieth century when the landscape was altered decisively by off-year Congressional elections–in 1910, 1930 and 1958. Each time, Democrats gained working majorities in the House and began acting on progressive or liberal ideas, even though a Republican President remained in office to block them. Most of those measures did not become law, but never mind. The action re-energized the opposition party and jump-started momentum that led to major reform eras–the presidencies of Wilson, Roosevelt, Kennedy and Johnson.

This time a national consensus for fundamental change has not yet formed, and the House Democrats look timid by comparison. But they have chosen a reality-based strategy that offers practical promises over big ideas. Their campaign theme, “A New Direction for America,” does not embrace big-spending goals like universal healthcare (the votes aren’t there yet). But it does promise action on bread-and-butter liberal legislation Democrats feel certain they can pass, at least in the House, and these issues speak to the everyday concerns of ordinary people.

It’s not Newt Gingrich’s “Contract With America,” the high-visibility stunt that accompanied the Republican blowout of 1994 but produced trivial results once the GOP controlled the House. The Democrats’ agenda is more cautious, but it has the virtue of being real–doable steps toward restoring the public’s faith in the efficacy of government. Dems reason that this election will be won or lost not by campaign rhetoric but on how voters feel about Bush and his war and the economy. Why confuse the issue with a grandiose wish list?

“In the first 100 hours of a new Congress, if elected,” minority leader Pelosi has declared, “Democrats will roll back the subsidies to Big Oil.” She means to repeal the tax relief and royalty giveaways Republicans enacted while oil prices and profits soared. House Democrats promise there will be no pay raise for Congress until Congress enacts the long-blocked increase in the minimum wage. They would also have the votes to pass what would be the most significant labor-law reform in at least four decades–“card check” certification for organizing unions that can liberate workers from the brutal unionbusting tactics of business.

Democrats intend to correct Bush’s malformed prescription drug program by allowing Medicare to use its vast bargaining power to lower drug prices. Other goodies for drug companies and HMOs will be removed. Dems expect to cut the interest rate on tuition loans and expand Pell grants. They would push for exit from Iraq, while implementing numerous homeland-security measures that the 9/11 commission recommended and Bush has ignored.

The objectives could get bigger and bolder if Democrats win control by a substantial majority, though no one is counting on that. Representative Pete Stark, the California liberal who would become chair of the health subcommittee of Ways and Means, has proposed a bill that essentially broadens Medicare coverage to include uninsured Americans. Stark said, “I would love, of course, and the Democratic Party would agree, to move toward universal coverage. But that’s not going to happen with a five-vote majority and no one in the White House pushing.”

Lots of other legislative issues have a good shot at House passage. Senior Democrats think their break from the past–Republican refusal to face these issues–will generate its own popular momentum for more action. Representative George Miller, another California liberal and Pelosi’s close policy adviser, would again become chair of the Committee on Education and the Workforce and is confident of winning on many matters.

“I have constructed the votes on a number of environmental issues or labor issues where I have a clear majority–230, 240 or 260 members who would vote for them,” Miller explains. “I can’t get that vote under the Republicans. After Gingrich and DeLay, the House became ‘winner take all.’ This most democratic institution now looks more like a bad Third World country where if you win an election, you get to shoot your opponents.”

Representative Barney Frank, the Massachusetts liberal who would chair the Committee on Financial Services, wants to legislate across a broad front and predicts, “We are going to frame these things so a lot of Republicans are going to have a hard time voting no.” His committee’s jurisdiction would let him take up predatory lending, unregulated hedge funds, consumer protection from financial fraud, Federal Reserve policy, the IMF and World Bank. He wants to give shareholders the power to reject the swollen pay packages awarded to corporate executives. He wants to start a major inquiry into income inequality, both in America and the global economy.

“The biggest difference will be housing,” Frank says. “We will get back in the business of building affordable housing. Republicans cut that out. That also means helping the homeless with social services. Housing is a big social problem, and now people understand it’s also an economic problem, not only for the poor but for the middle class.”

Perhaps most significant among the changes if the Democrats take over is that the new Democratic committee chairs would be able to launch myriad hearings and investigations–the oversight Republicans have virtually shut down. That includes contracting scandals and governing breakdowns in the executive branch, constitutional abuses by this President and the gaping holes in America’s system of elections. The House could become center stage for the war debate, with Bush’s lieutenants under oath required to answer their critics. Oversight is one of the core functions of Congress. Because Republicans have willfully shunned it, oversight hearings have the potential to expose scandal and produce shocking headlines. Pelosi was asked what was most important about regaining majority status. “Subpoena power,” she said.

The power to investigate has the potential to create the biggest waves in public opinion. Representative John Conyers promises, if he becomes chair of the Judiciary Committee, to initiate a preliminary inquiry into George W. Bush’s constitutional abuses. Representative Henry Waxman of the Government Reform Committee is “stunned” by the contracting waste, fraud and abuse in Iraq reconstruction, homeland security and the recovery from Hurricane Katrina.

Representative John Dingell of Energy and Commerce–the investigative master who taught a generation of younger Democrats how to do effective oversight–may look into the oil industry’s pricing and profit-making. Representative Ed Markey, who would chair the subcommittee on Telecommunications and the Internet, would take on the FCC’s lax supervision of the industry’s forming of monopolies, including corporate dominion and attempts to seize control of the Internet.

Even if such efforts succeed, they are only a prelude to big change. Reversing the party’s decades of retreat and defeatism is like turning a stalled ocean liner around. It takes time and patient steps, and these might be overtaken by larger events. The Democrats have a shot, if only they find the nerve to act aggressively on their opportunity.

Pelosi has the sure footing to step up the pace as circumstances improve, but she needs outside help. She will be aided if others turn up the heat on her, raising their expectations for what Democrats can achieve. The newly revived Progressive Caucus is already playing that role. Its members are now nearly one-third of the Democratic caucus. Co-chairs Lynn Woolsey and Barbara Lee will push big questions others aren’t yet ready to face–like cutting the military budget and reviving the commitment to eliminate poverty.

The outsiders in the party–rank-and-file voters, issue groups and ankle-biting bloggers–should get closer to the Congressional action and insinuate themselves as friendly critics of what the party is doing or afraid to do. Banging on Bush is always worthwhile, but banging on Democrats may now produce results.