The electoral arena matters too much to abandon it to gutless liberals, the extreme right wing, and corporate interests. The problem facing progressive insurgents is how to engage with it. In 1864, abolitionists debated whether to endorse Abraham Lincoln for reelection. (William Lloyd Garrison did so enthusiastically; Wendell Phillips supported a third-party candidacy.) After the New Deal cemented white working-class and Black voters to the Democratic Party, many in the labor movement bemoaned the absence of a true workers’ party. Moderate socialists, like Michael Harrington of the Democratic Socialist Organizing Committee, argued in the 1970s and ’80s that the Democratic Party constituted an American version of European social democratic parties, while a few leftists have experimented—with little success—with various third-party incarnations, from the Peace and Freedom Party in 1967 to the US Green Party, which still putter along today. Versions of these strategies compete for support in today’s reemerging political left.

With only 10.3 percent of US employees unionized last year, working people clearly need to build and wield greater political power. Toward that end, neither uncritical immersion in the liberal wing of the Democratic Party nor abstention from major-party politics is an effective strategy. Instead we need an inside-outside approach to electoral politics. We have to treat the Democratic Party not as an impenetrable monolith but as contestable terrain. We need an independent infrastructure, with its own staff, funding, base, and political capacity. But we also must reject the role of third-party spoiler and run candidates in primaries to unseat corporate Democrats.

The good news is that this plan is already underway, with a growing list of upset victories. It is not easy to beat the Democratic establishment, but Alexandria Ocasio-Cortez, Jamaal Bowman, Cori Bush, Rashida Tlaib, and many others have demonstrated that it can be done. Meanwhile, independent groups like Justice Democrats, the Sunrise Movement, Mijente, Dream Defenders, People’s Action, the Working Families Party, Democratic Socialists of America, and sections of the labor movement have revealed the critical role that independent movements and organizations can play in shifting the terms of debate, putting pressure on the power structure, and electing people’s champions. (The organization I cofounded, Pennsylvania Stands Up, is doing just that.)

We have a long way to go, but the insurgency has gained more traction than any other electoral attempt by the left in the past four decades. Our work now is to scale up. With each electoral cycle, we need to recruit more candidates, build stronger organizations, and develop more savvy campaigners and skilled organizers.

We are hitting our stride with a strategy that’s making measurable gains, and that should be argument enough. But let’s address the proposed alternative: exiting the Democratic Party to form our own labor party. The bottom line is that the United States’ winner-take-all voting system presents barriers to the emergence of a competitive third party that are insurmountable for the foreseeable future. A broad left political alignment can win in the US, but neither the Democrats nor a new leftist party can beat the GOP if they’re competing against each other. In US history, only the issue of slavery was sufficiently disruptive to give rise to a new party that could contend for majority support. And immediately afterward, the system contracted to two parties. Even the Great Depression—when a quarter of the nation was unemployed, millions of people were hungry and homeless, thousands of banks failed, and uprisings of the unemployed shook the political establishment—led to the transformation of the Democratic Party, not the emergence of another one.

A cursory look at the most recent consequential progressive third-party attempt, the US Green Party, shows why the path leads to a dead end. Ralph Nader had no strategy to win or to build power when he ran in 2000. Bernie Sanders, by running in Democratic presidential primaries, has done more to advance the left than the US Green Party has over its decades-long existence.

And the same thing would happen with any national-scale third party effort. Unless we can organize a successful constitutional convention, third parties are not going to be viable at the national level. And because they’re not viable, they will not attract serious leaders. (Consider Jill Stein and Howie Hawkins.) And without serious leaders, we will never build a mass party.

Fortunately, we don’t have to choose between a fantasy third party and the Democratic Party in its current state. We’re in the process of organizing a force to wrest the helm from the neoliberal old guard. We have a recent example that shows that a successful insurgency within a major party is possible: the Tea Party and Donald Trump. They took over the GOP and won the presidency with an unpopular agenda that excited their core base. Imagine what we can do running on a people’s agenda that enjoys widespread support.

To read the other side of The Debate, read Paul Blest’s “The Democratic Party Will Keep Betraying Labor. It’s Time to Launch a Workers’ Party.”