As the Democratic presidential candidates make their closing arguments to New Hampshire voters ahead of Tuesday’s primary, the leading contenders traded barbs on the Sunday morning news shows, with former South Bend, Ind., mayor Pete Buttigieg and Sen. Bernie Sanders (I-Vt.) fending off questions about their vulnerabilities.

Buttigieg, who has faced increasing attacks from his Democratic rivals after effectively tying Sanders for first place in last week’s Iowa caucuses, was asked to respond to a claim by former vice president Joe Biden that “this guy’s not a Barack Obama.”

“Well, he’s right. I’m not. And neither is he,” Buttigieg said of Biden on CNN’s “State of the Union.” “Neither is any of us running for president. And this isn’t 2008. It’s 2020. And we are in a new moment calling for a different kind of leadership.”

Buttigieg also responded to Sanders’s attack on him for raising money from wealthy donors.

“Bernie is pretty rich, and I would happily accept a contribution from him,” he said on CNN.

Sanders, meanwhile, pushed back against calls to release his medical records. The Vermont senator, the oldest major candidate for president in 2020, suffered a heart attack in October. He released information from three of his doctors in December stating that he had sustained “modest heart muscle damage” but is in good health and capable of doing the job.

“I mean, you can start releasing medical records, and it never ends,” Sanders said on NBC’s “Meet the Press” when asked whether he will release all of his medical records before Super Tuesday. “We’ve released a substantive part — all of our background. We have . . . cardiologists who are confirming that I am in good health. I am in good health.”

A chaotic Iowa caucus has left the Democratic Party scrambling for clarity in New Hampshire. (The Washington Post)

Seven candidates — Sanders, Buttigieg, Biden, Sen. Elizabeth Warren (D-Mass.), Sen. Amy Klobuchar (D-Minn.), entrepreneur Andrew Yang and investor Tom Steyer — battled onstage Friday night for the final Democratic debate before Tuesday’s New Hampshire primary.

But attention has focused on Sanders and Buttigieg after they came out on top in the Iowa caucuses. Biden — who finished fourth in Iowa behind Sanders, Buttigieg and Warren — has particularly sharpened his attacks against the leading candidates, calling Buttigieg inexperienced and questioning whether Sanders can follow through on any of his campaign promises.

The increasingly frantic tone of the campaign continued over the weekend at a New Hampshire Democratic Party dinner Saturday night in Manchester, where, one by one, the candidates made their pitches — as well as the same thinly veiled criticisms they had uttered earlier in the day.

Supporters on all sides cheered and booed. The tenor reflected candidates’ frustration that the race has remained stubbornly fluid. A new poll showed that roughly half of New Hampshire voters have not made up their minds with just days to go before Tuesday’s primary.

In an appearance on ABC’s “This Week,” Warren declined to say what will happen to her candidacy if she doesn’t finish in at least second place in New Hampshire after her third-place finish in Iowa.

“It’s going to be a long campaign,” Warren said.

Biden described the New Hampshire primary as “an uphill fight.”

“But it’s a fight that I think we’ll do well in,” he said in an interview with “This Week” that was taped Saturday.

Several of the candidates continued to voice frustration Sunday at the chaos surrounding this year’s Iowa caucus results.

Sanders said on CNN that the state’s Democratic Party “screwed it up very badly.” But he declined to echo others who have accused the Democratic National Committee of trying to hurt his campaign.

“I’m not casting any aspersions, political aspersions,” Sanders said, emphasizing that he believes he has an “excellent chance” of winning New Hampshire.

Democratic National Committee Chairman Tom Perez also expressed anger with the way the Iowa caucuses were run, calling it “undeniably unacceptable.”

“I’m frustrated. I’m mad as hell. Everybody is. And I think what we’re going to do at the end of this cycle . . . is have a further conversation about whether or not state parties should be running elections,” Perez said on CNN’s “State of the Union.”

He added that national Democrats will “absolutely” have a conversation after the November election about whether Iowa should retain its first-in-the-nation caucus status.

Chelsea Janes and Sean Sullivan contributed to this report.