Updated at 11:42 a.m. ET
In the final sprint before Tuesday's New Hampshire primary, Democratic presidential candidates are taking a more sharply negative tone about their rivals than they have up until now.
The top target is former South Bend, Ind., Mayor Pete Buttigieg. He faced a barrage of attacks as the other Democratic candidates seek to blunt his momentum from a strong showing in Iowa.
Former Vice President Joe Biden launched the most pointed attacks. Biden had mostly avoided criticizing his rivals by name before his disappointing fourth-place finish in Iowa.
A digital ad launched by Biden Saturday juxtaposes the former vice president's record with Buttigieg's as mayor. "We're electing a president," a narrator says. "What you've done matters."
The ad touts Biden's work on the Iran nuclear agreement, paired with Buttigieg loosening regulations on microchips for pets. The narrator highlights Biden passing the auto bailout, and then Buttigieg's revitalization of the sidewalks of South Bend with decorative brick.
Later, during a rare gaggle with reporters, Biden emphasized the point.
"I do not believe we're a party at risk if they nominate me, and I do believe we're a party at risk if we nominate someone who's never held a higher office than mayor of South Bend, Indiana," he said.
When asked whether it was fair to compare his spat with Buttigieg with Hillary Clinton's similar criticism of Barack Obama in 2008, Biden said, "Oh come on, man, this guy's not Barack Obama."
“He’s right, I’m not, and neither is he,” Pete Buttigieg tells @jaketapper when asked to respond to Joe Biden’s comment that “this guy's not Barack Obama” https://t.co/H9i18W6F1H #CNNSOTU pic.twitter.com/wEqM5SbQDi— State of the Union (@CNNSotu) February 9, 2020
Buttigieg shot back on CNN's State of the Union on Sunday: "Well, he's right," Buttigieg said. "I'm not [Obama], and neither is he. Neither is any of us running for president. And this isn't 2008; it's 2020. We are in a new moment, calling for a different kind of leadership."
Buttigieg's national press secretary, Chris Meagher, added in a statement: "The Vice President's decision to run this ad speaks more to where he currently stands in this race than it does about Pete's perspective as a mayor and a veteran."
Minnesota Sen. Amy Klobuchar, who's eager to gain support from the kind of moderate voters who back Buttigieg, also piled on with criticisms of Buttigieg's experience.
"We have a newcomer in the White House and look where it got us," she said on the debate stage Friday night. "I think having some experience is a good thing."
Buttigieg didn't shy away from his own criticisms of other candidates, taking subtle digs at Sen. Bernie Sanders, with whom he's locked in a virtual tie for first place in Iowa.
"I don't think we can take the risk of excluding anybody from this effort, of saying that if you're not either for a revolution or a status quo, then you don't fit. I think we're going to defeat this president by inviting everybody to be at our side and get this done together," Buttigieg said.
Sanders swiped back at Buttigieg during a rally in Dover on Saturday.
"Billionaires by the dozen are contributing to Pete Buttigieg's campaign," Sanders said. "Now, I like Pete, he's a smart guy, he's a nice guy. But if we are serious about political change in America, that change is not going to be coming from somebody who gets a lot of money from the CEOs of the pharmaceutical industry."
Buttigieg defended himself on this charge as well during the CNN interview, saying, "I'm not a fan of the current campaign finance system, but I'm also insistent that we've got to go into this with all the support we can get." To help make his point, Buttigieg cited how much money President Trump's re-election campaign has raised.
Biden has also gone after Sanders, saying the Vermont senator's self-avowed democratic socialism would make it hard to expand his base of support.
Sanders responded on Fox News Sunday, pivoting to discuss the tax breaks Trump himself got as a businessman and the corporate subsidies the federal government hands out to big companies.
"The difference between my socialism and Trump's socialism," Sanders said, "is I believe the government should help working families, not billionaires."
Sen. Elizabeth Warren is looking to improve on her third-place finish in Iowa.
But unlike some of her rivals, she's mainly stuck with a positive message so far and stayed out of the fray, seeking to position herself as a unifying candidate.
She did respond, though, when asked on ABC's This Week about Buttigieg's fundraising. She, like Sanders, is not accepting big-money contributions.
Sen. Elizabeth Warren responds to Pete Buttigieg, who defended taking money from billionaires, saying you need to build the biggest coalition you can.— This Week (@ThisWeekABC) February 9, 2020
“The coalition of billionaires is not exactly what’s going to carry us over the top,” Warren says. https://t.co/nPQ57Pvs7t pic.twitter.com/vMxPj5k7C6
"The coalition of billionaires is not exactly what's going to carry us over the top," Warren said.
The Massachusetts senator also looked ahead, past Tuesday's contest in next-door New Hampshire, where polls show her likely to finish third again.
"Look, the way I see this is it's going to be a long campaign," she said. "We've built a campaign to go the distance."