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– Democrats' hopes that New Hampshire voters might bring clarity to the chaotic fight for their party's presidential nomination were fading Monday as the state's primary election neared, with the wide swath of voters seeking a moderate candidate continuing to resist coalescing behind any one contender.

Vermont Sen. Bernie Sanders seems to be solidifying his support among voters on the party's left, boxing out Sen. Elizabeth Warren of Massachusetts, according to multiple polls of the state's voters, but the battle among centrists to leave New Hampshire as the clear alternative to him appears likely to continue long after candidates exit the state.

"This is just getting started," former Vice President Joe Biden said Monday on CBS' "This Morning."

Biden's plunge in support in the days leading up to Tuesday's primary has left the moderate lane wide open to other candidates, but he has sought to downplay the importance of New Hampshire and its heavily white electorate.

"Nothing is going to happen until we get to a place — and around the country — where there is much more diversity," he said.

Meanwhile, President Donald Trump, eager to put on a show of force in a general election battleground state, tried to rattle Democrats on Monday with a rally in New Hampshire on the eve of the state's first-in-the-nation primaries.

Trump mocked the lingering uncertainty over the outcome of the party's kickoff caucuses in Iowa, where the results are still under dispute. "Does anyone know who won Iowa?" he asked the crowd. "I don't know."

Trump narrowly lost New Hampshire in the 2016 election, and his campaign has targeted it as one that potentially could be flipped in 2020 and whose four electoral votes could make the difference in a close race.

Centrist Democratic voters have been bouncing among a cluster of candidates. Many have gravitated toward former South Bend, Ind., Mayor Pete Buttigieg, but tracking polls suggest his momentum may have stalled over the weekend as his rivals pounded away at him, with Biden in particular questioning his experience and fitness for office.

At a rally Monday morning in Plymouth, a small city in the central part of the state, Buttigieg continued his recent criticism of Sanders, saying that while "I respect his intentions," the Vermont senator was making promises he would be unable to keep without tax increases on the middle class.

"Look at Senator Sanders' math — $25 trillion worth of revenue" over the next 10 years, much of it in new taxes to pay for health care, Buttigieg said. Some of those taxes, including higher levies on the wealthiest Americans, "we can agree on," he said.

"But here's the problem, there's $50 trillion worth of spending. So about half of it is unaccounted for, and there's no explanation for where the other $25 trillion is supposed to come from."

An American majority exists for major, progressive change, he said, but not "if we take it all the way to the extreme."

Sanders has said in interviews that he does not believe voters expect him to lay out a complete accounting of taxes and spending at this stage of the campaign.

Non-party voters likely will make up more than 40% of the turnout in Tuesday's election. In 2016, independents delivered the lion's share of their votes to Sanders as he competed against Hillary Clinton, who was the choice of establishment Democrats.

The Associated Press contributed to this report.