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MANCHESTER, N.H. — Former Vice President Joe Biden delivered his most stinging attacks on Pete Buttigieg yet Saturday, mocking his mayoral accomplishments in an online campaign ad and dismissing him as "not a Barack Obama."

The escalation came as candidates have piled on Buttigieg in the days leading up to New Hampshire's crucial first-in-the-nation primary, following the claim of victory by the former mayor of South Bend, Indiana, in the chaotic Iowa caucuses and Biden's underwhelming fourth-place finish there.

Saturday evening, the candidates shared a stage with the rest of the field at the McIntyre-Shaheen dinner in Manchester, delivering speeches before a packed arena of New Hampshire Democrats.

In the 90-second ad, Biden contrasted his efforts to help pass the Violence Against Women Act, the Affordable Care Act, a ban on assault weapons, as well as his work to negotiate the Iran nuclear deal and boost the Midwest's economy with Buttigieg's work installing "decorative lights," loosening regulations on pet chip scanners and "laying out decorative brick" on South Bend sidewalks.

The ad also highlighted Buttigieg's controversial firing of his city's first African American police chief.

"We’re electing a president," the ad concludes. "What you’ve done matters."

Former Mayor Pete doesn’t think very highly of the Obama-Biden record. Let’s compare. pic.twitter.com/132TB7MHaq — Joe Biden (Text Join to 30330) (@JoeBiden) February 8, 2020

In remarks to reporters at his campaign office in Manchester on Saturday afternoon, Biden dismissed Buttigieg's rising candidacy.

"Oh, come on, man," Biden said. "This guy is not a Barack Obama. Barack Obama had been a United States senator of a really large state. Barack Obama had laid out a clear vision of what he thought the international society should look like. Barack Obama had laid out in detail what he thought should happen to the economy.”

In response to a question from NBC News, Biden maintained that he didn’t want Democrats to form a circular firing squad, but “when you get attacked, you’ve got to respond."

"I’ve kept my mouth shut for a long time” as Buttigieg has made the “constant assertion that, somehow, the problems we’re facing today are because of our administration," he said.

Without mentioning Biden by name, Buttigieg pushed back. "Now, I know some folks are out there saying, what business does a mayor of South Bend have running for the presidency?" he told supporters at a rally on the Dartmouth College campus Saturday.

"You don't have an office in Washington, your community is little out of the way," he continued. "What I'm saying is, that that's exactly the point."

"We're tired of being reduced to a punchline by Washington politicians," he said at a later event in Lebanon.

On Sunday, Buttigieg pushed back directly on Biden's most eye-grabbing line.

"He’s right, I’m not [Obama]," Buttigieg told "Fox News Sunday." "And neither is he."

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The episode is a carryover of one of the more contentious moments of Friday night's New Hampshire debate, when Buttigieg said it was best to leave "the politics of the past in the past" — to which Biden responded, "The politics of the past, I think, were not all that bad."

"I don’t know what about the past of Barack Obama and Joe Biden was so bad," he added.

New Hampshire polling has virtually flipped in the days following the Iowa vote. About three weeks ago, Biden held a 10-point edge on Buttigieg in the Granite State; he now trails the ex-mayor by about 10 points, with Sanders in the top spot, according to the RealClearPolitics average of several polls.

Buttigieg holds a 10-point lead on Biden in a CNN/University of New Hampshire poll released this weekend. And he holds an 8-point lead over Biden in an NBC News/Marist poll released Friday.

In the opening minutes of Friday's debate, Biden even seemed to concede he would fare poorly in Tuesday's vote. "I took a hit in Iowa, and I'll probably take a hit here," he said then. On Saturday, he pushed back on the gloomy headlines his assessment had sparked. "The reports of my death are premature," he told reporters in Manchester.

Responding directly to Biden's ad, Buttigieg campaign manager Chris Meagher said voters want "something completely different from this classic Washington style of politics."

"While Washington politics trivializes what goes on in communities like South Bend, South Bend residents who now have better jobs, rising income, and new life in their city don't think their lives are a Washington politician's punchline," he continued. "Pete’s on-the-ground experience as mayor, turning around a Midwestern industrial city, is exactly why he is running for president. 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 veteran.”

In a subsequent campaign fundraising email, the Buttigieg campaign wrote the "biggest risk" Democrats could take in the primary is selecting a nominee to "go up against this president with the same old playbook."

Nan Whaley, the mayor of Dayton, Ohio, and a prominent Buttigieg backer, was among the mayors taking issue with Biden's ad Saturday.

"I’m from Dayton, population 140,371," she tweeted. "Are you saying voices from our towns don't matter?"

Symone Sanders, a senior adviser to the Biden campaign, said the former vice president was in no way mocking the work of mayors and small-town politicians.

"Let’s be really clear here, Joe Biden started life as an elected as a county councilman," she tweeted. "He knows the power of local government. So he knows what mayors CAN do. The question here is what HAVE you done and are you ready to be commander in chief on day one? Joe Biden is."

Two sources familiar with the Biden campaign's thinking said the idea behind the ad was that while it may draw pushback, the controversy will deliver the attention it needs to go viral, drawing attention to Buttigieg's relative inexperience.

As Biden's hits on Buttigieg have gained traction, Sen. Bernie Sanders, I-Vt., has remained relatively unscathed through the weekend. Though Biden was critical of the senator's brand of "democratic socialism" both in Saturday events and at the debate, he focused much more energy on Buttigieg. As it stands, Sanders holds a lead in New Hampshire polls and claimed victory in Iowa.

Listing achievements from his career, Biden asked a Manchester crowd Saturday whether Buttigieg was "really saying that the Obama-Biden administration was a failure?" He also took aim at Buttigieg's relatively low level of support among black Americans.

"Mayor Pete likes to say the only time Democrats win the presidency is when we nominate someone new," he said. "But here's what he never mentions. The only Democrats to win the presidency is where we have overwhelming support from the African American community and don't take it for granted."

"This is a diverse party, it's the reason why we are strong," he continued. "Our nominee has to reflect that strength."

Buttigieg's relative inexperience on the national stage has come under fire from other opponents as well. "We have a newcomer in the White House, and look where it got us," Sen. Amy Klobuchar, D-Minn., said during Friday's debate, pitching herself in closing remarks as "not a political newcomer with no record."

NBC News asked Klobuchar on Saturday about the brewing Biden-Buttigieg brouhaha and Buttigieg's record. "I was the first one who rang that bell," she said.

Amid the escalation, many voters who came to see Biden speak Saturday in Manchester said they were torn between him and Buttigieg.

In interviews, these Democrats said they appreciated Biden’s readiness for the job, but wondered if he’d lost a step — and that they were attracted to Buttigieg’s intelligence and demeanor, but worried he might be unready for the world’s biggest job.

"I saw [Biden] at the debate last night. He was a little iffy," said Moranda Gagnon, a health services worker from Manchester who’s undecided between Biden and Buttigieg.

"The age thing does concern me with Biden,” Gagnon said, adding that she’s sympathetic to his point about Buttigieg’s lack of experience: "I agree about the inexperience. I mean, look at what we have in the White House right now with the inexperience."

Lee Stembel of Long Island, New York, who was visiting New Hampshire and attended Biden’s event, said he was torn among Biden, Buttigieg and Klobuchar in the Democratic primary.

Stembel said he had been "a little concerned by Biden’s lack of energy," but he was sympathetic to his criticism of Buttigieg, suggesting that the former mayor could help himself by announcing a team of knowledgeable advisers he can tap to help him address national problems.

"I think [Biden] took a reasonable shot at Pete. Pete lacks experience,” Stembel said.