GILFORD, N.H. — When Joe Biden entered the presidential race in April, his greatest asset was his perceived strength — the sense among Democrats that he would be their best candidate to face President Donald Trump in the fall.

But one week after a disappointing finish in Iowa, the former vice president's campaign is bracing for a similar result in New Hampshire on Tuesday — or perhaps an even worse showing, given a late surge in support for Sen. Amy Klobuchar, D-Minn. — and scrambling to deal with a vicious cycle in which questions about his viability only feed more doubt.

The former vice president pushed back Monday morning on the idea his campaign was in trouble.

"I'm going down to two very diverse states next, and I expect to do very well there," Biden told NBC News after his first event Monday in Gilford. "And still nationally I'm still leading in all the polls that I'm aware of. Number two, the endorsements keep coming in."

Asked what his path forward was, Biden said: "The path is South Carolina and going into Nevada and going into Super Tuesday, and going into states that I'm going to do very well in."

Biden has slipped in both New Hampshire and national polls since his fourth-place finish in Iowa. Seeking to reverse his slide, Biden launched his most aggressive attack against a fellow Democrat to date on Saturday, with a snarky campaign video diminishing Pete Buttigieg's work as mayor of South Bend, Indiana, in comparison to his as vice president. He amplified the attack on the campaign trail that day.

But some inside the campaign and allies on the outside saw it as a risky strategy, running contrary to Biden's brand and giving Buttigieg an opening to counterattack. Just a day later, Biden was no longer hitting the former mayor on the trail during a pair of town hall meetings. In fact, at one stop he even suggested Buttigieg would make a good running mate because of their agreement on key issues like health care.

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Biden insisted again on Monday that he was only responding to Buttigieg's slights, which he viewed as criticism of the Obama administration.

"He said basically Barack Obama and I didn't do much at all, and the problem started before this president became president," he said. "We did a pretty good job."

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"He's a great guy," Biden continued. "He was a great mayor. But let me tell you something, you know of that Recovery Act, we sent $65 million of it to his city. So I mean comparing what I have done — everything from arms control to getting health care passed — to the rest to his record, that's all I was doing, responding."

Biden added that he has stood by for months as his rivals took aim at him.

"Who has had more attacks sent to them than anybody in the race by a factor of five? Me. Because I've been the front-runner, remained the front-runner nationally. I've got a target on my back," he said. "There are certain things you got to clarify though."

Adding to the sense of dread within the Biden campaign is how his disappointing showing in Iowa has enabled his rivals to chip away at what were seen as his unique selling points to voters. Klobuchar has gained momentum as she pitches herself as a pragmatic, accomplished moderate. Buttigieg, who is openly gay, has tried to seize President Barack Obama's mantle by playing up a message of generational change and the potentially historic nature of his candidacy. And billionaire ex-New York Mayor Michael Bloomberg, another moderate with executive experience in business and government, is bombarding Trump on the airwaves with an unprecedented television advertising campaign presenting himself as the best candidate to take on Trump in the general election.

The advantage the Biden campaign insists it still holds over the field is his bedrock support with African American voters. Senior adviser Symone Sanders and some of the former vice president's African American surrogates are fanning out in the press on Monday to make the case that Democrats need to hear from black voters in states like South Carolina and those with primaries on Super Tuesday.

"Whatever happens on Tuesday, Vice President Biden will still be in this race," Sanders said of the New Hampshire contest in a CNN interview Monday morning.

Biden told volunteers during an afternoon stop at his Salem field office that he was likely to stop in South Carolina this week, before heading to Nevada. Asked by NBC News if that state was a must-win, Biden said only that it was "important."

But South Carolina votes 18 days after New Hampshire and a week after Nevada, meaning that another disappointing finish in the Granite State will force the candidate and his campaign to endure more brutal news cycles and questions about his viability.

Biden said there was no reason for concern among his supporters.

"What evidence is there of anybody being concerned? I've seen none of it," he said. "All I see is support coming in."

Biden said in an interview earlier Monday on "CBS This Morning" that his campaign was raising "about a half a million dollars a day."

Senior advisers insist that Biden, whose campaign has struggled financially, will have the resources to compete into Super Tuesday on March 3 — although none will deny they would like to have more cash to spend.

Sanders told NBC this weekend, "We're having a number of new office openings in our Super Tuesday states this week, in Alabama and Virginia and North Carolina and, yes, in California. So, we plan to compete.

"He's not out of this race," she continued. "And I really think it would be a mistake for anyone to count Joe Biden out. Count Joe Biden out at your own risk."