Washington (CNN) PBS NewsHour and Politico are co-hosting the last primary debate of 2019, which will show seven presidential contenders facing off against each other less than 50 days before voting starts in Iowa.

Thursday's debate, airing live on CNN, will feature the smallest and least diverse field of candidates so far in the race for the White House.

The debate comes one day after President Donald Trump was impeached in a historic vote at a deeply divided and tumultuous time in US history.

It also comes days after a labor dispute between a California union and a catering provider threatened to derail the high-profile event. All seven Democratic presidential candidates who met the qualifications said they would not participate in the debate if they had to cross the union's picket line. The union announced Tuesday that an agreement was reached.

What time is the debate?

The debate is at 8 p.m. ET, and will take place at Loyola Marymount University in Los Angeles, California.

How can I watch it?

In addition to airing on local PBS stations, the debate will air exclusively on CNN, CNN International, CNN en Español, and stream on CNN.com, PBS.com's home page, and Politico.com's homepage. The debate will also be available across mobile devices via CNN's apps for iOS and Android, via CNNgo apps for Apple TV, Roku, Amazon Fire, Chromecast and Android TV and SiriusXM Channels 116, 454, 795.

Who is moderating?

PBS NewsHour's Judy Woodruff, Amna Nawaz and Yamiche Alcindor and Politico's Tim Alberta will moderate the debate.

Who is participating?

Former Vice President Joe Biden

South Bend, Indiana, Mayor Pete Buttigieg

Minnesota Sen. Amy Klobuchar

Vermont Sen. Bernie Sanders

Businessman Tom Steyer

Massachusetts Sen. Elizabeth Warren

Entrepreneur Andrew Yang

Who didn't make the cut?

Colorado Sen. Michael Bennet

Former New York City Mayor Michael Bloomberg

New Jersey Sen. Cory Booker

Former Secretary of Housing and Urban Development Julián Castro

Former Maryland Rep. John Delaney

Hawaii Rep. Tulsi Gabbard

Former Massachusetts Gov. Deval Patrick

Author Marianne Williamson

How was the stage decided?

Democratic candidates needed to receive 4% in at least four national or early state polls that met the DNC's criteria, or 6% in two early state polls. Candidates had to also receive donations from at least 200,000 unique donors, with a minimum of 800 from at least 20 different states. The DNC has been raising the thresholds for the contests, slowly shrinking the field of Democrats on the high-profile debate stages.

What happened at the last debate?

At the fifth Democratic presidential debate in November, the leading Democratic candidates made strong appeals to African American voters -- particularly women -- and drew a direct line between recreating the coalition that elected Barack Obama in 2008 and defeating President Donald Trump in 2020.

Debating in a Deep South state where black voters will likely be the majority of the Democratic electorate in the March primary, the discussion over who could best represent that community drew the most fireworks in an otherwise civil debate among the 2020 candidates in Atlanta. Questions from the MSNBC/Washington Post moderators on the thorny topic of race drew charged exchanges between Booker and Biden, as well as Buttigieg and Harris, who has since dropped out.

The debate struck at the core of the electability argument taking place within the primary. Both Booker and Harris, the two black candidates on stage, argued that Democrats must nominate a candidate in 2020 who understands the issues facing those communities if the party intends to activate and bring out enough voters on Election Day to defeat Trump.

Biden's solid support from black female voters, who have so often been the linchpin for successful Democratic nominees, has bolstered his standing in the polls, particularly in states like South Carolina. Booker, Harris, Buttigieg and Warren all sought to loosen his grip on that key constituency in the debate.