What to watch for in tonight's Democratic debate

What to know: Tonight's lineup is the smallest we've seen all year, with just seven Democrats appearing on stage: Joe Biden, Elizabeth Warren, Bernie Sanders, Pete Buttigieg, Amy Klobuchar, Andrew Yang and Tom Steyer.

• That (hopefully) means an opportunity for greater depth in questions and answers.
• It's a unique moment for billionaire Steyer, who in 2017 launched the "Need to Impeach" movement targeting Trump — long before most of his peers were on board — and got 8.4 million people to sign on.
• The debate is taking place in Kamala Harris' home state just weeks after she dropped out of the race.
• Without Harris — or Cory Booker and Julian Castro, who didn't meet the qualifications for this debate — that leaves one person of color on the stage (Yang) in a year that counts the most diverse primary field in history.

The big picture: Roughly 24 hours after the House of Representatives impeached Trump, competing Democrats will make their cases for why they're best positioned to defeat him.

• If past trends continue, there will be a camp calling to unite the country post-Trump (Biden and Buttigieg); calling for a complete overhaul of the system (Sanders and Warren); and using impeachment to take on Senate Majority Leader Mitch McConnell as the real “villain” in all this (Klobuchar).

Don't forget: There are three U.S. senators on stage tonight (Warren, Sanders and Klobuchar) who will be plucked from the campaign trail when the trial goes to the Senate next month.

• Expect them to be asked how they will balance that and campaigning for president at a crucial time in the race, just weeks before the Iowa and New Hampshire.

Candidates also are likely to be asked about the labor union dispute between Loyola Marymount University food service workers and Sodexo, a food services and facilities management providers, that prompted all seven Democrats to threaten to boycott tonight's debate. A tentative deal to settle the dispute was reached on Tuesday.

Between the lines: Sanders has been climbing in the polls in recent weeks, re-establishing himself in second place as Warren has slipped slightly. He's also received endorsements from some of the star freshman Democrats, like Reps. Alexandria Ocasio-Cortez, Ilhan Omar and Rashida Tlaib.

• That makes tonight especially crucial for him, as a stumble could stunt that growth — just as a stellar performance could solidify it.
• Watch for whether tonight is the first time he and Warren have a real spat over health care.

One more thing: Buttigieg is still facing questions about a lack of support from black voters and his record on race in South Bend, Indiana, as the city's mayor has risen to frontrunner status in Iowa.

• That will almost certainly come up tonight. The South Bend Black Lives Matter chapter held a call with reporters this morning to outline their disappointment in Buttigieg's record.
• Melina Abdullah, a professor of Pan-African Studies at California State University-Los Angeles, and a national Black Lives Matter leader, views Buttigieg's policies for the black community as a form of "liberal white supremacy" that "spews inclusive rhetoric" but is ultimately about "oppression" of people of color.
• But Buttigieg was endorsed this week by Kareemah Fowler, the CFO for the South Bend Community School Corp., a former city clerk and an African-American woman, who said he had inspired her to advance her career in public service and has tackled systemic racism and the racial wealth gap.

Go deeper: Where the candidates stand on the issues, in under 500 words