Expect the gloves to come off when Democratic presidential hopefuls square off in Detroit.

The field of 20 White House hopefuls will do battle Tuesday and Wednesday in round two of debates in the crowded bid for the party’s presidential nomination in 2020.

The stakes are high – only eight have qualified for September debates – and former Vice President Joe Biden needs to shake off a stumble-filled performance last month.

Biden, 76, later admitted he “wasn’t prepared” for round one, when Sen. Kamala Harris of California put a dent in the Democratic front-runner’s lead when she criticized his record on school busing and working with segregationists.

“It was hurtful to hear you talk about the reputations of two United States senators who build their reputations and careers on the segregation of race in this country,” Harris berated Biden over his comments about working with segregationists in the past.

“It is not only that, but you also worked with them to oppose busing,” she said.

The debates will air on CNN at 8 p.m. tonight and tomorrow, with the field randomly divided. CNN will also livestream the events.

Moderated by Dana Bash, Don Lemon and Jake Tapper, candidates will be given 60 seconds to respond to moderators’ questions and 30-second rebuttals.

A candidate singled out by another will have 30 seconds to respond. There will be no show of hands or one-word questions. Candidates who consistently interrupt will lose time.

On the stage on Tuesday will be Rep. Beto O’Rourke of Texas, Montana Gov. Steve Bullock, author and activist Marianne Williamson, former Rep. John Delaney, former Colorado Gov. John Hickenlooper, Rep. Tim Ryan of Ohio, Minnesota Sen. Amy Klobuchar, South Bend, Ind., Mayor Pete Buttigieg, Sen. Elizabeth Warren of Massachusetts and Vermont Sen. Bernie Sanders.

The following night will feature Biden, Harris, Mayor Bill de Blasio, Washington Gov. Jay Inslee, Sen. Kirsten Gillibrand of New York, Rep. Tulsi Gabbard of Hawaii, Colorado Sen. Michael Bennet, New Jersey Sen. Cory Booker, entrepreneur Andrew Yang and Julián Castro, former housing secretary in the Obama administration.

This week’s debate will be a make-or-break night for most of the Democratic hopefuls, including de Blasio, who’s been scrambling to stay in the race and meet the threshold to qualify for the September debates in the Democratic race.

De Blasio is desperately asking for $1 donations to meet the 130,000-contributor threshold to qualify for the third debates in September.

“I want to make an appeal to your listeners,” the mayor said last Friday on the “Laura Coates Show” on Sirius XM.

“If you believe in things like a bill of rights for workers please help me. Donate at least $1 online at BilldeBlasio.com. Help me stay on that debate stage.”

The mayor’s campaign said Monday that he had “a very good first debate performance, but knows this one is different and he will be ready to perform accordingly.”

“He’s practicing opening and closing remarks, drills and honing responses to specific candidates, and is being fueled by chips and guacamole, mixed nuts and water,” press secretary Jacklyn Rothenberg said in a statement.

Also desperate to make a splash are low-polling candidates including Bullock, Inslee and O’Rourke, who’s seen his support slide.