For the sixth time in half a year, a winnowing field of Democratic hopefuls will take to the stage for a presidential primary debate. If November’s snoozefest could best be described as the debate no one in America wanted, December’s gathering at Loyola Marymount University in Los Angeles might be called the debate that almost didn’t happen.

Last week, all seven qualifying Democrats—led by Massachusetts Senator Elizabeth Warren— pledged to boycott tonight’s debate due to a deteriorating labor dispute between campus food service giant Sodexo and the service union workers of UNITE HERE Local 11. The union “is fighting for better wages and benefits—and I stand with them,” tweeted Massachusetts Senator Elizabeth Warren. Bernie Sanders and the rest of the field quickly followed with a pledge not to cross the picket line.

The standoff caused heartburn in Washington for Democratic National Committee Chair Tom Perez, who faced the possibility of an embarrassing rift between Democrats and key allies in the labor movement. Fortunately for Perez and the subset of Americans who enjoy the peculiar masochism of watching every moment of America’s unending 2020 presidential contest, Sodexo and UNITED HERE Local 11 reached a tentative agreement just days before the debate.

America’s imperiled labor movement offers moderators an excellent starting point for a deeper conversation on the Democratic Party’s commitment to unions and fair labor practices. The challenges facing food service workers at Loyola Marymount University are not unfolding in a bubble: across the country, food service workers are locked in a multi-year fight to secure a $15 minimum wage. Farmworkers from states as diverse as Florida and New York have campaigned for better working conditions and protections from sexual assault and labor exploitation. The gig economy has decimated wages.

Loyola Marymount University’s sunny California locale also provides Democrats with an opportunity to pay respect to the new wave of organizers challenging labor’s once formidable influence on Democratic Party policymaking. Long the central force in Democratic campaigns of the 20th Century, labor has seen its primacy challenged as the Democratic Party fills with new and competing interest groups from Millennials, LGBTQ+ voices, and immigration activists to resurgent environmentalists and racial justice organizers.

Each of those groups rose to prominence by creating their own seats at an often insular Democratic decision-making table. That creates something of an optics nightmare for Democrats: aside from entrepreneur and long-shot candidate Andrew Yang, every face on the stage tonight is white. Only two, Warren and Minnesota Senator Amy Klobuchar, are women.

That tonight’s debate is in California, a racially diverse state represented by former candidate Senator Kamala Harris, only sharpened criticism from activists and 2020 contenders like New Jersey Senator Cory Booker, who are increasingly concerned the Democratic Party pays lip service to representation while doing little to foster it in practice. Proposed changes to future debate qualifying criteria may be too little, too late to shake up an increasingly set 2020 roster.

No one would benefit from a larger debate stage more than South Bend Mayor Pete Buttigieg, whose sharp rise in Iowa and New Hampshire has drawn heavy fire from Sanders, Warren, and the liberal voices that make up self-styled “Political Twitter.” Buttigieg escaped the November debate largely unscathed--a decision his rivals now consider a major tactical error. If December has been any indication, candidates to Buttigieg’s left won’t make the same mistake twice.

The Warren campaign has spent the past month hammering Buttigieg for details on his time as a junior employee at international consulting firm McKinsey. Buttigieg fired back, calling on Warren to release tax returns from her time as a corporate lawyer. Bernie Sanders recently slammed Buttigieg’s health care plan as “a failed idea” and criticized a recent Buttigieg fundraiser in Napa Valley for courting wealthy donors reviled by Sanders’ liberal supporters.

So far, there isn’t much evidence the Warren and Sanders barrage has done much to harm Buttigieg’s 3-5 point lead in Iowa. Few voters are paying close attention to an exhausting primary campaign that is still more than a month away from the first Iowa votes. But that may not be true during a nationally televised debate. Buttigieg can expect to face more focused criticism tonight than at any prior point in his campaign. Democratic Party influencers will be watching how he handles the pressure.

And then there’s Joe Biden.

The Democratic frontrunner has been a nearly invisible presence since the November debate. Steady though his polling may be, Biden’s campaign expects to lose both Iowa and New Hampshire. More dangerous for Biden any weakness in his commanding South Carolina margin. A recent Post and Courier poll suggests Biden’s once commanding 24-point lead now sits below 10. Even if the Post and Courier poll represents an unreliable outlier, Biden’s opponents are now spending millions to weaken his hold on the state.

“ As has become normal for Biden, his muddled, hesitant campaign leaves him vulnerable on both flanks. ”

Biden has now debated his Democratic rivals half a dozen times, and rarely has he walked off the stage stronger for the effort. Tonight will be an opportunity to see how Biden handles more time in the spotlight and a chance for voters to gauge whether he has a compelling message and strategy for surviving an increasingly hostile Democratic primary.

A strong performance by Sanders or Warren could further erode Biden’s shaky fundraising. The Biden team is also aware that a tentative truce with Buttigieg has turned off supporters who expected Biden to more vigorously defend his center lane from a Buttigieg takeover. As has become normal for Biden, his muddled, hesitant campaign leaves him vulnerable on both flanks.

The most pressing question hasn’t changed: who can beat Donald Trump? The first Democratic debates in June drew around 18 million viewers. Last month that number fell below 7 million, and a Suffolk poll revealed nearly two-thirds of likely Iowa voters didn’t even tune in. Trump’s impeachment may sharpen the focus for voters determined to prevent a second Trump term at all costs.

Tonight’s debate offers Democraitc hopefuls have a final chance to convince the party faithful they can best Trump before voters head to the polls in February. For a nation facing the constitutional crisis of impeachment, the stakes couldn’t be higher.