If Ms. Warren was the dominant figure in the debate, Mr. Sanders was perhaps the luckiest: The front-runner in Nevada and national polls, he emerged largely unscathed from the debate as his moderate rivals focused on ripping into Mr. Bloomberg and one another. After Mr. Sanders’s victory in the New Hampshire primary and his tie in the Iowa caucuses, he is the best positioned in the field to keep building momentum heading into the Nevada caucuses, the South Carolina primary and the Super Tuesday contests in 16 states and territories three days later on March 3.
Advisers to another top candidate, former Mayor Pete Buttigieg, said after the debate that they believed he accomplished his primary objective of painting Mr. Bloomberg and Mr. Sanders as extremists within the Democratic Party while establishing himself as the candidate best capable of building a coalition to defeat Mr. Trump.
To that end, they said, his other objective was to disqualify Senator Amy Klobuchar of Minnesota as a centrist contender. Mr. Buttigieg repeatedly attacked Ms. Klobuchar, who was the surprise third-place finisher in the New Hampshire primary, in hopes of hobbling her in Nevada and beyond and cutting into her base of support.
Mr. Biden, whom Mr. Buttigieg attacked relentlessly in Iowa, is no longer seen as a serious threat.
“The reason Pete has been so frustrating for people to understand is because he’s bringing new people into the system that weren’t there last time,” said Jon Soltz, the co-founder of VoteVets, whose super PAC is backing Mr. Buttigieg. “Pete’s obituary has been written a lot and nobody’s been right. There he is going toe to toe in a debate last night as the candidate with the most delegates for the presidency.”
The onslaught of criticism against Mr. Bloomberg tested one of his campaign’s central assumptions: that he should avoid attacking his rivals in the interest of staying above the fray that has consumed the race for the Democratic nomination. Mr. Bloomberg has run, in essence, a parallel campaign from the other candidates over the last two and a half months, skipping Iowa, New Hampshire, Nevada and South Carolina to focus instead on the states that vote in the Super Tuesday contests.
But the fray came to him — in the form of attacks over his defense of policing practices that targeted minorities and accusations that he is using his vast fortune to “buy the election.”
If Wednesday night’s debate threw doubt on Mr. Bloomberg’s ability to make the case to voters that he is the strongest general election competitor to Mr. Trump, the campaign could take solace in the fact that their candidate would not appear on the ballot in any state for nearly two weeks.