Portsmouth, New Hampshire - As former United States Vice President Joe Biden continues to see his poll numbers sink in New Hampshire in advance of the state's primary election on Tuesday, a new duel is coming into political focus.

With Biden's support in New Hampshire falling from a poll average about 23 percent to 11 percent among the many Democratic candidates for president, former South Bend, Indiana, Mayor Pete Buttigieg has emerged as a favourite for the party's moderate wing. But Senator Bernie Sanders, from the neighbouring state of Vermont, still appears to hold a healthy lead over Buttigieg as the two trade increasingly vicious barbs.

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"Sanders is kind of the least of the evils right now," said Willa Shaw, an employee at Treehouse Toys in Portsmouth.

Democratic US presidential candidate Senator Bernie Sanders poses with students for selfie photographs after speaking at a campaign rally one day before the New Hampshire presidential primary election in Rindge, New Hampshire [Mike Segar/Reuters]

"I'm not very politically informed, but I feel like I do have to vote," she told Al Jazeera, adding that Sanders will hopefully be able to win the Democratic primary and then the general election.

'40 billionaires'

Over the weekend, the contrast between the two sharpened. Sanders has painted a picture of Buttigieg as a young, inexperienced centrist candidate under the thumb of billionaires.

The US senator told fired-up supporters in the town of Plymouth that the 38-year-old had raised campaign cash "from over 40 billionaires".

"We're taking on Wall Street," Sanders said to rousing cheers. "We're taking on the insurance companies. We're taking on the drug companies. We're taking on the fossil fuel industry. We are taking on the military-industrial complex."

For his part, Buttigieg warned about the costs of Sanders's Medicare-for-all plan. In Dover, he alleged that the 78-year-old "has no idea how [Medicare for all] is supposed to be paid for".

Pete Buttigieg, Democratic presidential candidate and former South Bend, Indiana, mayor, attends a campaign event in Plymouth, New Hampshire [Eric Thayer/Reuters]

The Democratic Party, meanwhile, has been doing its best to recover from the Iowa caucus voting disaster in which neither Sanders nor Buttigieg could claim outright victory. Both have called for a recanvass of the results.

Biden on Monday looked to be competing for third place in New Hampshire with Massachusetts Senator Elizabeth Warren, whose fortunes have also declined nationally and who was polling first in the state just months ago.

US Senator Elizabeth Warren speaking at a campaign town hall in Lebanon, New Hampshire, US [Brian Snyder/Reuters]

"She could be a surprise, a come-from-behind candidate," said Rachel Collins, a college volunteer from Florida canvassing in New Hampshire for Warren.

"I think Sanders does have a good chance," Collins told Al Jazeera. "But I worry about what happens after New Hampshire, and I don't know if the Democratic Party is ready to unite behind either candidate."

But Biden has not let Buttigieg off easy either, with an advertisement on Saturday criticising the ex-mayor's short tenure in government. The elder statesman from Delaware also brought up the issue of support from the crucial African American community.

Leading in the next primary states of Nevada and South Carolina, Biden seems more likely to gain traction in those relatively diverse places.

Former Vice President Joe Biden speaking to supporters at a campaign event in Hampton, New Hampshire [Elise Amendola/AP Photo]

'Klobucharge'

Since New Hampshire's Democratic primary is "open", all of the candidates - but particularly the moderates - are canvassing for independent and Republican votes, too.

A Monmouth University poll released Friday on the eve of the New Hampshire debate showed that just under half of the state's primary voters were already decided on their preferred candidates.

Many voters are now fleeing to Senator Amy Klobuchar for the lack of what they see as other viable contenders to take on President Donald Trump in November.

Democratic 2020 US presidential candidate Senator Amy Klobuchar is greeted by supporters during a campaign event in Salem, New Hampshire [Brendan McDermid/Reuters]

Klobuchar's rallies have been attracting bigger numbers across the state, most recently in Keene, where her supporters filled up an overflow room because the initial amount of space did not suffice.

The "Klobucharge" has propelled her to third place in some polls on the eve of the primary.

Analysts say this is the result of voters thinking Sanders is too far left and believing that Buttigieg - whose improbable rise has shocked many - just does not have a long-enough political resume.

New Hampshire's primary comes after a chaotic Iowa caucuses [Ben Piven/Al Jazeera]

But even for those who support other candidates, including entrepreneur Andrew Yang, the race will ultimately come down to who voters are able to relate to more.

"We went to the Buttigieg town hall yesterday, said Joshua Harrison, a Yang supporter. "He's able to rock the stage."

"His message is a very safe one, whereas Bernie is a candidate for a future very different from what we have right now," Harrison told Al Jazeera.

"Their rivalry will come down to who is most relatable. And that's why I give the edge to Buttigieg."