Grading Bloomberg, Sanders and other Democrats at the Las Vegas debate: Mastio & Lawrence

David: The news of the night was Elizabeth Warren. After disappointing showings in Iowa and New Hampshire, she needed to show she was still fighting and still had a reason to stay in the race. She's sure still fighting. She nuked Mike Bloomberg, but I don't think that will get her many votes.

Jill: You are right about Warren, the question is how many Democrats want that level of combativeness and believe it's the way to beat President Donald Trump. There's more than one way to go after him and each other, as other candidates showed.

Now, on to the grades ...

Former Vice President Joe Biden

David: C-. Biden had a good night compared to some of his other debates, but he really needed to shine to make the case that he is on the road to a comeback. Did his performance shake things up enough to stop his supporters from continuing to drift away? Nope.

Jill: B+. Biden had an energetic and focused evening. He showed several times that he could react spontaneously in the moment, but not all his debate appearances have been at this level. Could Democrats count on him to come through in a race against Trump? Also, Biden pointed to polls as proof of his superior electability, but his two bad losses in Iowa and New Hampshire have deflated that argument.

Former New York City Mayor Mike Bloomberg

David: F. The former mayor was slapped down hard by Warren and he never really seemed to regain his footing. His half-hearted excuses on stop and frisk won't do anything to put that issue to bed. His muddled answer on releasing women from their non-disclosure agreements with him or his companies left him looking foolish. He was either unprepared for obvious attacks or he isn't up to the debate format. Now we find out whether all his money can protect him from the demise that would face any other candidate.

Jill: D. Quite a rude initiation for Bloomberg. He seemed at times exasperated that he had to deal with these lesser (and so much less rich) mortals onstage with him. He was unapologetic about his wealth and evasive regarding the terrible things he’s said about women. He did apologize for stop and frisk, but as Bernie Sanders noted, that record will not exactly inspire Democrats to vote in droves. There's another debate Tuesday. He probably wishes he hadn't qualified.

Former South Bend, Indiana, Mayor Pete Buttigieg

David: C. Mayor Pete need to show that he was the front-runner in the center lane. Perhaps that is why he went after Sen. Amy Klobuchar so hard on multiple fronts, especially her fumble on questions about Mexico. He didn't overshadow the senator or former vice president Joe Biden enough to put either of them away. It is still a 4-way race to see who emerges as the competitor with socialist Bernie Sanders.

Jill: A. Buttigieg was on the attack as much as anyone else in this ferocious debate, but he has a kind of genius for twisting the knife in a reasonable tone of voice. It was easy to see how a debate with Trump would go as he lectured Sanders that “you’re not the only one” who cares about the working class and told him his contingent of abusive followers is evidence he’s failing a leadership test. Buttigieg uses humor to good effect and thinks on his feet better than anyone else in the race. That's not nothing.

Minnesota Sen. Amy Klobuchar

David: D. Klobuchar wasn't making any sense to me tonight. She crumbled under attack for her lack of knowledge about Mexico. Some of her rehearsed lines came across as garbled. "When you see troubled waters, you don't blow up a bridge, you build one." What? Her idea that nominating a woman will cut back on Internet sexism seems naive. She positively dripped with contempt for Mayor Pete at points. It wasn't a good look.

Jill: B. Like Buttigieg, Klobuchar is good at lightening the mood. "I must say I take personal offense because Post-It notes were invented in my state," she joked after Warren dismissed her health plan as a Post-It note. Klobuchar correctly pointed out that she has more experience and larger wins than Buttigieg, and suggested she might even have lower blood pressure. She clearly believes she needs to KO Buttigieg right out of the race. I'm not sure that's going to happen, and the multiple-moderates situation will get even more complicated if Biden's revival has legs.

Vermont Sen. Bernie Sanders

David: B. Bernie needed to be Bernie and not let anyone knock him off his game. Mission accomplished. Did he do anything more than that? Not really.

Jill: B+. You don’t have to like Sanders’ politics to recognize his political strengths. But he doesn’t think he’s polarizing (he is) and he thinks Bloomberg’s Republican past and billionaire status are fatal political flaws. "I would be very surprised” if that’s the way to beat Trump, he said. But quite a few Democrats seem to think it could be. Maybe because they’re terrified of Sanders as their nominee.

Massachusetts Sen. Elizabeth Warren

David: C. Sen. Warren had the same job as Biden tonight: Make it clear why she was still in this with a plausible chance to win. She sure delivered some tough blows to Bloomberg, but in the race with the rest of her opponents, I don't think she changed anything.

Jill: A/D. You either love or hate Warren. Either way, she was peak Warren, starting right out with her attack on Bloomberg — as she stood beside him — as "a billionaire who calls women fat broads and horse-faced lesbians." She said Democrats would take a huge risk "if we just substitute one arrogant billionaire for another." But Warren is risky, too. Her performance likely convinced some that she's exactly what they need, and others that she's the last thing.

David Mastio, a libertarian conservative, is the deputy editor of USA TODAY's editorial page. Jill Lawrence, a center-left liberal, is the commentary editor of USA TODAY. Follow them on Twitter: @DavidMastio and @JillDLawrence

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This article originally appeared on USA TODAY: Democratic debate in Las Vegas: Grading the 2020 candidates from A to F