ARI SHAPIRO, HOST:

Last night's Democratic debate in Las Vegas set a record - it was the most watched Democratic debate ever, according to NBC News. That might be good for the TV network airing it, but for Mike Bloomberg, maybe not so much.

MARY LOUISE KELLY, HOST:

Yeah. His debut debate performance is being widely criticized today. The former New York mayor's campaign is framing it as a warm-up with another chance at another debate next week in South Carolina. So where does the race stand now? A question for NPR senior political editor and correspondent Domenico Montanaro.

Hey, Domenico.

DOMENICO MONTANARO, BYLINE: Hello.

KELLY: The thing about Mike Bloomberg is he has spent so much money on ads introducing himself to voters. Has being able to control the message insulated him from having to spar on his feet?

MONTANARO: Maybe. I mean, to a degree that may be true. He has spent some $400 million trying to refine his image. But given the high ratings of the debate, like you guys talked about, and the negative reviews that have followed, Bloomberg may have become the most polarizing figure in the party. He's particularly disliked by progressives, especially for his comments last night about women and those nondisclosure agreements at his company.

So look - he's no unity candidate. There's certainly no coalescing around him from moderates. So he just seems to be threatening to pull even more support from former Vice President Joe Biden, former Mayor Pete Buttigieg and Senator Amy Klobuchar of Minnesota. And that is not what Bloomberg wanted to accomplish with this debate performance. There was always going to be a huge degree of skepticism with Democrats of a business executive over 70 who's a billionaire - so I'll leave that there.

KELLY: What about Bernie Sanders, the front-runner in this race at this point? He largely avoided attacks last night. His rivals were going after each other instead. Does he remain the front-runner? Does he continue his march toward the nomination?

MONTANARO: I mean, the chaos does nothing but help him. The more divided everyone else is, that means he's got the inside track of getting the most delegates - you know, maybe not a majority of those delegates, but a chunk to a quarter - you know, of a quarter to 30%, which is what he's been pulling in so far, may be enough to help him get a pledged delegate lead. You know, and he has this devoted and unshakable base of progressives and young people. The longer moderates go without picking one person, the more likely it is that Sanders becomes the nominee.

But let's watch Elizabeth Warren. She's been fighting with him on this progressive lane. She came out guns blazing last night, even went after Sanders. She's got a shot in Nevada, where she has pretty good organization to show that she's back.

KELLY: You just used the word delegates over and over and over...

MONTANARO: (Laughter).

KELLY: ...Because this is all about the delegates.

MONTANARO: It's a delegate race.

KELLY: You need a majority of them - yeah - at the national convention to win the nomination. But there is already talk of a contested convention, one where nobody has an outright majority going in. That led to a really interesting exchange. I want to play this for you. This is last night's debate - NBC News.

(SOUNDBITE OF ARCHIVED RECORDING)

CHUCK TODD: Leading person with the delegates - should they be the nominee or not?

JOE BIDEN: No, let the process work its way out.

TODD: Mayor Buttigieg?

PETE BUTTIGIEG: Not necessarily. Not till there's a majority.

TODD: Senator Klobuchar?

AMY KLOBUCHAR: Let the process work.

TODD: Senator Sanders?

BERNIE SANDERS: Well, the process includes 500 superdelegates on the second ballot.

TODD: All right.

SANDERS: So I think that the will of the people should prevail.

TODD: OK.

SANDERS: Yes.

TODD: Thank you, guys.

SANDERS: The person with the most votes should become the nominee.

TODD: Five noes and a yes.

(APPLAUSE)

KELLY: Senator Sanders there...

MONTANARO: (Laughter).

KELLY: ...Talking about the process versus the will of the people. Walk us through the process. How is it supposed to work?

MONTANARO: To clear things up here, what we know from that is that Bernie Sanders is the only person on the stage who thinks the person with the pledged delegate lead should be the nominee. And the longtime rules set out by the Democratic National Committee that all the campaigns have signed on to is that you need a 50% plus-one majority to be the nominee. That - this year, that magic number is 1,991. With such a splintered field, it's hard to see how somebody, you know, gets that.

Of course, they want the majority of the entire party behind that candidate. But he mentioned superdelegates, which could be really important because their role has changed this year.

KELLY: Yeah. Just briefly - how has it changed?

MONTANARO: Yeah. Look - these are these longtime party officials, and there's about 700 of them. They had their superpower stripped - they can't vote on the first ballot, but they'll be able to vote on that second ballot. We could be calling them super zombie delegates because they - their votes may come back to haunt some candidate in the end.

KELLY: Super zombie delegates - a phrase to tuck in your pocket and keep paying attention to.

NPR's Domenico Montanaro, thanks.

MONTANARO: You're welcome. Transcript provided by NPR, Copyright NPR.