LAS VEGAS — The Democratic presidential candidates turned on one another in scorching and personal terms in a debate Wednesday night, with two of the leading candidates, Sen. Bernie Sanders and Michael Bloomberg, forced onto the defensive repeatedly throughout the evening.

In his first appearance in a presidential debate, Bloomberg, the former mayor of New York City, struggled from the start to address his past support for stop-and-frisk policing and the allegations he has faced over the years of crude and disrespectful behavior toward women. Time and again, Bloomberg had obvious difficulty countering criticism that could threaten him in a Democratic Party that counts women and African Americans among its most important constituencies.

Two candidates who have shied away from direct conflict in past debates, Sen. Elizabeth Warren of Massachusetts and former Vice President Joe Biden, mounted something of a tag-team onslaught against Bloomberg, several times leaving him visibly irked and straining to respond.


From the first seconds, when Sanders used the initial question to attack what he called Bloomberg’s “outrageous” policing record, it was clear that this debate would be far more heated than any of the previous forums. The unrelenting attacks reflected the urgency of the moment, as Sanders gains strength and those hoping to slow his candidacy are increasingly crowded out by Bloomberg and his unprecedented spending spree.

Warren landed the most stinging blows against Bloomberg throughout the debate, starting with an opening broadside that likened him to the figure most reviled among Democrats: President Donald Trump.

“I’d like to talk about who we’re running against: a billionaire who calls women fat broads and horse-faced lesbians,” Warren said. “And no, I’m not talking about Donald Trump. I’m talking about Mayor Bloomberg.”


It was not only Sanders and Bloomberg who were subjected to withering criticism: Sen. Amy Klobuchar of Minnesota and former Mayor Pete Buttigieg of South Bend, Indiana, also engaged in a bitter and lengthy colloquy about foreign policy and their qualifications for the presidency, culminating in a sharp exchange in which Klobuchar asked Buttigieg if he was calling her “dumb.”

There was little in the first hour of the debate to suggest that Sanders, currently the national front-runner and the favorite to win Nevada’s caucuses Saturday, had been knocked off balance, and the pile-on against Bloomberg had the potential to work in Sanders’ favor by keeping the focus of hostilities elsewhere.

But Sanders, too, was pressed to address some of the persistent questions about his candidacy, including whether he would release a fuller version of his medical records and why his candidacy appears to inspire uniquely vitriolic behavior by some of his supporters on the internet. Sanders, Vermont’s junior senator, insisted that nearly all of his online fans were good and decent people, but said he would “disown those people” who behave in deplorable ways.

In the exchange that may have damaged Bloomberg the most, Warren repeatedly demanded to know whether he would be willing to release some of the former female employees at his media organization from the nondisclosure agreements they had signed. He declined to do so, calling the agreements “consensual,” and minimized the underlying complaints by suggesting that the women merely “didn’t like a joke I told.”

After pressing Bloomberg and leaving him flustered, but unable to coax him into releasing the women she said he had “muzzled,” Warren then broadened her attack.

“We are not going to beat Donald Trump with a man who has who-knows-how-many nondisclosure agreements and the drip, drip, drip of stories of women saying they have been harassed and discriminated against,” she said.


And before Bloomberg could even try to defend himself, Biden, who has seen the former New York mayor claim some of his support, gladly stepped in. “All the mayor has to say is, You are released from the NDA, period,” Biden said, his voice rising.

The debate figured to be a strenuous test for both Sanders, as an emerging front-runner, and Bloomberg, whose free-spending campaign has established him as a leading candidate despite having never previously participated in a presidential debate or interacted directly with any of the other Democrats in the race. Polls released over the past few days have found Sanders opening up a substantial lead among Democratic voters nationally, with Bloomberg overtaking Biden as a moderate runner-up.

The rivalry between Sanders and Bloomberg has turned harshly personal this week, as their campaigns escalated a feud that both see as serving their political interests. On the morning of the debate, aides to Bloomberg and Sanders were trading slashing criticism about the health of the two men, who are both 78 years old, and transparency about their medical histories.

Kevin Sheekey, Bloomberg’s campaign manager, on Twitter invoked Sanders’ recent heart attack to pressure him to release more medical records, while Briahna Joy Gray, a spokeswoman for Sanders, falsely claimed that Bloomberg had also had a heart attack. She later backtracked, instead citing a cardiac procedure Bloomberg had in 2000.

The rise of Sanders and Bloomberg has complicated the path forward for the other candidates who can match neither Sanders’ powerful fundraising operation and grassroots following, nor Bloomberg’s limitless personal wealth and saturation-level advertising. Even Biden, the onetime favorite for the nomination, has struggled to assert himself in recent weeks, in a campaign increasingly defined by a democratic socialist promising revolution and an ultrabillionaire presenting himself as a centrist savior.

For Bloomberg, the debate was an opportunity to establish himself not just as an alternative to Sanders, but as a dominant leader of the party’s moderate wing. His advisers have long believed his path to the nomination will require him to sideline Biden before the Super Tuesday primaries in early March, and gather up a big coalition of voters concerned about the sweep of Sanders’ ideas or his ability to prevail in the general election.


Bloomberg may have already stifled the prospects of other moderates, including Buttigieg and Klobuchar, who have gained only a little ground in national polling as Bloomberg’s commercials have lifted his numbers across the country.

But it remains unclear whether Bloomberg might actually be in a position to accomplish that feat. After months of campaigning apart from the other candidates, Bloomberg has found his record and character under sustained and exacting scrutiny for the first time, and he has spent much of the past week grappling with questions about his stance on law enforcement, his conduct toward women and his vast wealth.

In the run-up to the debate, nearly all of the other Democratic candidates telegraphed their intentions to aggressively go after Bloomberg, with Sanders and Warren leveling especially fierce criticism of the former mayor’s policing policies and his spending in the presidential race. Warren has repeatedly challenged Bloomberg to void nondisclosure agreements with several women who have made sexual-harassment and hostile-workplace claims related to Bloomberg and his financial-information company, Bloomberg LP.

Biden, too, has spoken up about Bloomberg’s relationship with black voters in New York City, and his campaign has complained that Bloomberg is running ads that falsely imply he has the support of former President Barack Obama.

Sanders is also facing newly blunt opposition from other Democrats.

For much of the past year he was either ignored, referred to obliquely or used as a foil in the service of critiques aimed at other candidates. But after he finished at the top in Iowa and New Hampshire, and with polls showing him leading in Nevada, Sanders is emerging as the clear front-runner in the Democratic race. And that almost certainly means he will face attacks from his opponents about both his left-wing politics and the ugly behavior of some of his supporters.

In the days leading up to the debate, a number of the candidates denounced the personal attacks that Sanders supporters aimed at the female leaders of the influential union of Las Vegas’ casino employees, the culinary workers’ union.


If the other contenders are not able to slow Sanders in Nevada, he may gain enough momentum going into the Super Tuesday contests on March 3, when 15 states and territories will vote, to eventually claim the nomination. But if he falters here, it could throw the race open and create an opportunity for one or more of his rivals to assert themselves. No candidate may be more cognizant of these stakes than Biden, who finished in a distant fourth in Iowa and an even worse fifth in New Hampshire.

The former vice president is now trying to play down his struggles in the first two states, pointing to their monochromatic demography while projecting optimism about his prospects in the more diverse Nevada and South Carolina, which votes a week from Saturday. In Nevada, he enjoys the support of much of the local Democratic establishment, including two prominent members of the congressional delegation, Dina Titus and Steven Horsford, and the state’s lieutenant governor, Kate Marshall.

Yet by trumpeting his hopes for a strong finish in Nevada — he told donors last week he would finish in the top two — Biden is only raising expectations about his potential and making it harder to explain away another poor showing.

Buttigieg and Klobuchar, who finished strong in Iowa and New Hampshire in part because of their skillful criticism of Sanders, have kept up that offensive in Nevada. Even Warren, who for months avoided any conflict with her fellow progressive, has grown more willing to address their differences, and this week she said Sanders should be accountable for the bullying behavior of many of his supporters online.