Buoyed by a strong showing in last week's Iowa contest, Sanders for the first time claimed national frontrunner status in a new poll that also showed billionaire Michael Bloomberg -- who is skipping Tuesday's contest -- vaulting into third place behind a struggling Joe Biden.

Firing up his supporters with promises to slash inequalities and overhaul America's health care system, the 78-year-old Sanders -- who represents neighboring Vermont in the Senate -- appeared to have an unassailable lead in New Hampshire, where he won the primary by a landslide in 2016.

Bernie Sanders and Pete Buttigieg came top of the first contest in Iowa, giving each important momentum Bernie Sanders and Pete Buttigieg came top of the first contest in Iowa, giving each important momentum Photo: AFP / Joseph Prezioso

"Let us win the Democratic nomination, let us defeat Donald Trump, let us transform this country," Sanders urged a Sunday night rally, where he took the stage to a deafening roar and chants of "Bernie! Bernie!"

Bernie Sanders, a leftist whose state borders New Hampshire and who won there by a landslide in 2016, holds a firm poll lead ahead of the upcoming primary Bernie Sanders, a leftist whose state borders New Hampshire and who won there by a landslide in 2016, holds a firm poll lead ahead of the upcoming primary Photo: AFP / Joseph Prezioso

The RealClearPolitics polling average showed Sanders at 28.8 percent in New Hampshire, tailed on 22.3 percent by his moderate rival Buttigieg -- the 38-year-old former mayor of South Bend, Indiana who was proclaimed winner in Iowa in a boost to his long-shot White house bid.

As the frontrunners glad-handed their way across snowy New Hampshire, a late surge also lifted the fortunes of Amy Klobuchar, with two new polls showing the senator from Minnesota jumping past heavyweights Biden and Elizabeth Warren to notch up 14 percent support.

Democrat Pete Buttigieg has faced increasingly sharp criticism for his lack of national experience Democrat Pete Buttigieg has faced increasingly sharp criticism for his lack of national experience Photo: AFP / Joseph Prezioso

Like Iowa, New Hampshire is viewed as a crucial litmus test for Democrats hoping to challenge Trump in November, especially for former vice president Biden and senator Warren, whose campaigns appear to have hit a wall.

US Democratic primaries and caucuses US Democratic primaries and caucuses Photo: AFP / Jonathan WALTER

In what it called a "dramatic shift," a new Quinnipiac University poll showed Sanders for the first time overtaking Biden in the national nomination race, attracting 25 percent support against 17 percent for Biden -- who has been shaken by a fourth-place finish in Iowa.

But in a surprise twist, the poll also showed Bloomberg jumping from eight to 15 percent support since January 28, suggesting an upset could be in store when the former mayor of New York -- who is skipping the first four nominating contests -- throws himself fully into the race.

Only a few days ahead of the New Hampshire election, some visitors at an ice castle and fishing competition give primary politics the cold shoulder.Duration:01:12 Only a few days ahead of the New Hampshire election, some visitors at an ice castle and fishing competition give primary politics the cold shoulder.Duration:01:12 Photo: AFPTV / Agnes BUN

Bloomberg is focusing on Super Tuesday on March 3, when 14 states vote -- having spent a record $260 million of his personal fortune on his campaign, to the anger of Sanders who accuses him of trying to "buy the election."

Supporters of US Presidential Candidate Senator Bernie Sanders cheer and wave campaign signs as they await his arrival at a campaign rally at Keene State College in Keene, New Hampshire on February 9, 2020. Supporters of US Presidential Candidate Senator Bernie Sanders cheer and wave campaign signs as they await his arrival at a campaign rally at Keene State College in Keene, New Hampshire on February 9, 2020. Photo: AFP / Joseph Prezioso

A new national poll shows billionaire Michael Bloomberg vaulting into third place in the US Democratic nomination race A new national poll shows billionaire Michael Bloomberg vaulting into third place in the US Democratic nomination race Photo: AFP / Mark Felix

Eager to upstage the Democrats -- and riding high after surviving his impeachment trial with his electoral support seemingly intact -- Trump has summoned his supporters to an election eve rally of his own in Manchester, New Hampshire, promising "big crowds."

"Want to shake up the Dems a little bit -- they have a really boring deal going on," he tweeted.

In a sign of the high stakes, the Democratic race has taken a bad-tempered turn in recent days with Sanders and Buttigieg trading barbs, and Biden and Klobuchar sharpening their attacks on both frontrunners.

Sanders -- whose campaign, based heavily on small donors, says it raised $25 million last month -- has branded Buttigieg the candidate of Wall Street.

"Unlike other campaigns, we don't have billionaires giving huge amounts of money," he said Sunday night.

Buttigieg pushed right back, quipping, "Well, Bernie's pretty rich, and I would happily accept a contribution from him."

The first gay politician to be a serious contender for the White House, Buttigieg has been proclaimed winner of last week's Iowa caucuses, but an array of problems in the nominating contest undercut his narrow victory over Sanders.

As Buttigieg has risen from practical anonymity, he has also faced intensifying criticism -- including in a cutting weekend ad by the Biden camp -- for his lack of national experience and supposed difficulty connecting with black voters, a key demographic.

After listening to Buttigieg at a rally in Nashua, New Hampshire on Sunday, Katie Morgan, 20, told AFP that he was "interesting and smart."

But she added, "I personally prefer a candidate with a little more experience."

Both Buttigieg and Biden, meanwhile, have said it would be much harder for the party to defeat Trump with Sanders, a socialist, as the candidate.

But Sanders' position at the very left of the American spectrum -- with programs like extending the Medicare program to all Americans -- has been eagerly seized on by the president, who said last week, "I think he's a communist."