MANCHESTER, N.H. — The Democratic campaign entered a more combustible phase Friday as the party’s candidates attacked each other on a debate stage with blistering policy critiques and arguments over who was best positioned to beat President Trump in November.

With no clear front-runner and four days to go before the New Hampshire primary, seven of the party’s leading candidates abandoned the wonky policy contrasts and opaque tonal critiques that had filled the race before Monday’s caucuses in Iowa. The debate stage became a free-fire zone instead, the candidates seizing the moment to call each other out.

They harped on age and political records, flashed anger and indignation, and warned their rivals’ policy prescriptions would fail. Multiple candidates cautioned that the polling leader, Sen. Bernie Sanders (I-Vt.), would not be electable given his identification as a democratic socialist.

In a sign of the reordering of the Democratic primary race, it was Sanders and former South Bend, Ind., mayor Pete Buttigieg who often took control of the stage, engaging in impassioned monologues — and seeing their records scrutinized — while rivals raised their hands in the hopes of being called on next.

Former vice president Joe Biden and Sen. Elizabeth Warren (D-Mass.) entered the evening looking to break out of their sudden second-tier status, as billionaire former New York mayor Mike Bloomberg, while not on the ballot or on the debate stage here, continues to increase his campaign spending in the hopes of upsetting the race when he begins appearing on ballots next month.

In one of the most pointed parries, Buttigieg, 38, attacked Biden’s longevity in politics, suggesting the party should not “fall back on the familiar” and urging voters to “finally allow us to leave the politics of the past in the past.”

“The politics of the past were not all that bad!” Biden, 77, interjected, pointing toward measures on violence against women, arms control and other legislation he shepherded over the course of more than four decades as a U.S. senator and vice president.

“I don’t know what about the past of Barack Obama and Joe Biden that were so bad,” he said.

Buttigieg also turned toward Sanders, saying a nominee can’t be someone “dividing people with a politics that says if you don’t go all the way to the edge, it doesn’t count. A politics that says it’s my way or the highway.

“Politics should be one of addition and inclusion and belonging,” he said, “not one that beats people over the head and says they shouldn’t even be on our side if we don’t agree 100 percent of the time.” Asked if he was referring to Sanders, Buttigieg said yes.

“I’ve never said that,” Sanders, 78, responded. “But let me tell you what I do say. The way you bring people together is by presenting an agenda that works for the working people of this country, not for the billionaire class.”

Although absent, Bloomberg came under unified condemnation from the stage.

“It’s a funny thing,” Sanders said. “There are millions of people who can desire to run for office. But I guess if you’re worth $60 billion and you can spend several hundred million dollars on commercials, you have a slight advantage. That is nonsense.”

Sen. Amy Klobuchar (D-Minn.) agreed: “I don’t think people look at the guy in the White House and say ‘We need someone richer.’ ”

Biden was more pointed with his rivals than in past debates but seemed to struggle at times to get his message across, while Warren kept her answers focused on the campaign messages she has been delivering for months. Klobuchar, 59, had her strongest debate showing so far, making a direct appeal to a New Hampshire electorate filled with moderates.

“I do not have the biggest name up on this stage. I don’t have the biggest bank account. I’m not a political newcomer with no record,” she said. “But I have a record of fighting for people … If you are tired of the extremes in our politics and the noise and the nonsense, you have a home with me.”

Klobuchar went up against both Sanders and — in another chapter in an ongoing dispute — Buttigieg. She reminded Buttigieg of a line he used regularly in Iowa during the impeachment trial in which he called the proceedings “exhausting” enough to make him want to change the channel and watch cartoons instead.

After a lively and rambunctious start, however, the candidates also tried to show some form of unity. Buttigieg defended Biden, saying Democrats should not worry about Republican threats to investigate Biden and his son Hunter.

“We’re not going to let them change the subject. This is not about Hunter Biden or vice president Biden or any Biden,” he said. “This is about abuse of power by the president. The vice president and all of us are competing, but we’ve got to draw the line somewhere.”

Biden went over to hug Sanders at one point, both of them displaying wide grins. Warren, 70, tried to cast herself as a unifying candidate and generally refrained from some of the intraparty squabbling.

“Bernie and I’ve been friends for a long time,” she said. “We have a lot of things in common. We have a lot of things that we differ on. But, you know, this fundamental question about how we bring our party together, we have to think about it in new ways.”

The sudden shift of dynamics after Monday’s Iowa caucuses has raised concern among party leaders that there will be no quick conclusion to the nominating process, potentially forcing a drawn-out contest that deepens party divisions and leads to a weakened nominee.

“I don’t think there’s any question, after this week, that Donald Trump can get reelected,” business executive Tom Steyer said, repeatedly returning to the anxiety coursing through the party. “We have got to win or we are in deep trouble.”

Even Sanders, who won more popular votes in the Iowa caucuses than any other candidate, admitted that the turnout in the state did not reach the levels of the 2008 election. “That’s a disappointment,” Sanders said. “And I think all of us probably could have done a better job turning out our supporters.”

Parts of the party are worried about Buttigieg’s limited experience and Sanders’s democratic socialist identity. At the same time, Biden’s claim on electability was undercut by his fourth-place finish in Iowa, and Warren, overshadowed with her third-place finish, has been trying to avoid an embarrassing result Tuesday next door to her home state of Massachusetts.

Biden took critical time away from the campaign trail this week to spend two days at home in Wilmington, Del., as he prepared for the debate, met with advisers and restructured his campaign. In an effort to calm skittish donors and supporters, his campaign confirmed Friday that it was giving greater responsibility to adviser Anita Dunn.

“I took a hit in Iowa and I will probably take a hit here,” Biden said in his first answer of the evening.

In a sign of the financial strain the candidates are feeling as the race drags on, several made direct appeals for money from the audience viewing on television.

Since Buttigieg last took a debate stage, his stature in the race has changed dramatically. His surprisingly strong Iowa finish lifted him into a collision course with Sanders here, though by and large, they appeal to different groups within the party.

Buttigieg challenged Biden’s assertion that the party needs to nominate a safe bet — which Biden defines as himself — arguing that the bigger risk would be to nominate someone who represents the old ways of doing things.

“The perspective I’m bringing is from somebody whose life has been shaped by the decisions made in those big white buildings [in Washington],” Buttigieg said. “We need a perspective . . . that will allow us to leave the politics of the past in the past.”

His opponents cast him as naive.

“We have a newcomer in the White House right now and look where it got us,” Klobuchar said. “I think having some experience is a good thing.”

Business executive Andrew Yang, who has run a cheerful campaign and drawn outsized crowds to his economy-infused message, has limited time left to make an impact.

“Let me say, America, it’s great to be back on the debate stage,” Yang, who is 44, said, referring to missing the qualifications for the previous debate. “I’m so excited. I want to give every American $1,000 a month.

More than they have in past debates, the candidates took issue with each other’s records. Biden said Sanders should be held accountable for his votes against gun-control legislation — and that it’s not enough for him to claim that he was just representing constituents in a hunting-friendly state.

“Bernie, while you were representing your constituency, an awful lot of people . . . in California, New York, Pennsylvania, they’re getting killed by the thousands during the same period,” Biden said.

Sanders said he has evolved on the issue. “The world has changed and my views have changed,” he said.

The group of mostly white candidates had one of its most extended discussions on race and criminal justice issues. The candidates squabbled over their past records, and comments from surrogates, with a focus on the black electorate that will dominate South Carolina’s Feb. 29 primary.

Steyer, 70, twice pressed Biden to apologize for what he and some supporters considered to be racist comments made by one of Biden’s top supporters in South Carolina. (Biden said the supporter, state senator Dick Harpootlian, was sorry.) Biden then urged Sanders to answer for comments made in a South Carolina newspaper by one of his supporters made about his history on matters of race. (“Joe Biden is a friend of mine and I’m not here to attack him,” Sanders said).

Buttigieg, who has struggled for support among minority voters, was asked about racial disparities in the criminal justice system in South Bend during his tenure — in particular, the increase in arrests of black citizens for marijuana possession.

“We adopted a strategy that said drug enforcement would be targeted in cases where there was a connection to the most violent group or gang connected to a murder. These things are all connected, but that’s the point,” he said. “So are all of the things that need to change in order to prevent violence and remove the effects of systemic racism, not just from criminal justice but from our economy from health from housing and from our democracy itself.”

Warren was then asked whether Buttigieg’s answer was substantial enough.

“No,” she said. “You have to own up to the facts.”