Vermont Senator Bernie Sanders was expected to square off with Pete Buttigieg, former mayor of South Bend, Indiana, on Tuesday in New Hampshire's primary election, with the first group of voters casting ballots in several small towns.

A solid win by either could generate the momentum needed to win primaries in other states－and help the victor secure the Democratic Party's presidential nomination, analysts said.

"The New Hampshire race is between Sanders and Buttigieg," Jonathan Zogby, CEO of research company Zogby Analytics, told China Daily. "I think whoever wins Tuesday gains momentum and has the potential to become the nominee."

Or, a result with no clear winner could further complicate the road to the nomination, especially if former vice-president Joe Biden finishes far behind and creates an opening for former New York mayor Mike Bloomberg, who is not participating in the New Hampshire primary.

Such an outcome likely would further spur Bloomberg's willingness to dip into his personal fortune in an effort to win the Democratic nomination and challenge Republican President Donald Trump in November.

"Bloomberg has spent about $250 million so far and moved up in the polls," Zogby said. "He may do well in some East and West Coast states, but can he win over voters in states like Ohio, Michigan and Wisconsin where Trump resonated with blue-collar voters? Being a Manhattan billionaire will make it tough－and I don't know if he will be able to buy his way to the nomination."

In the New Hampshire race, polls released on Monday by the University of Massachusetts-Lowell, Boston Globe/WBZ-TV/Suffolk University, 7News/Emerson College and CBS News/YouGov show Sanders leading with as much as 25 to 30 percent of the vote, up about two points.

Buttigieg polled as high as 19 percent, up as much as five points from a week ago, while Massachusetts Senator Elizabeth Warren dropped as much as four points and Biden fell as much as eight points, according to various polls.

On the eve of the primary, pollsters said the race generally stacked up this way: Sanders leads and is followed by Buttigieg, US Senator Amy Klobuchar of Minnesota, Warren and Biden. However, the CBS poll shows Biden leading Klobuchar by two points－within the poll's margin of error and therefore a statistical tie.

Campaigns

Sanders won the popular vote in the Iowa caucuses, but under the rules for that state, Buttigieg received more delegates than Sanders to the July 13-16 nominating convention in Milwaukee, Wisconsin.

On Monday, Buttigieg said in Plymouth, New Hampshire, that nominating Sanders risks "alienating Americans at this critical moment".

Sanders countered by saying that: "You have the option to vote for a campaign which will not only defeat Trump but which will transform this country."

Klobuchar highlighted her centrist views and poll results. "I didn't have a big name going into this, but what I have is grit," she told voters in Keene, New Hampshire.

In Nashua, New Hampshire, Biden greeted school bus drivers, and offered doughnuts from "one school bus driver to another". Biden said he had driven school buses as a law student at Syracuse University. "Look me over, OK?" he said.

Warren walked about 3 kilometers through the snow in Conway, New Hampshire, wearing a hat that said "Make Earth Cool Again".

Bloomberg, founder of the financial news service bearing his name, with an estimated fortune of $61.5 billion, is the unknown factor in the Democratic primaries.

He has not contested the early races, but has spent millions to build name recognition for Super Tuesday－March 3, when voters in 15 US states, including California, Texas and North Carolina cast ballots.

Bloomberg, elected twice as a Republican and once as an independent, served three successful terms as mayor of New York. But he's not a dynamic campaigner and may be out of step with current Democratic primary voters because of his wealth and pro-business outlook.

A Quinnipiac national poll of Democrats showed that Sanders received 25 percent of the vote and pulled ahead of Biden with 17 percent. Bloomberg received 15 percent, up 8 points from a poll on Jan 28.

James Carville, the strategist who masterminded Bill Clinton's 1992 presidential victory and his 1996 reelection, said Democrats are squandering their chance to defeat a vulnerable president by focusing on politically toxic issues such as open borders, tax increases, increased regulation of the economy, forgiving college loans, letting criminals vote from prison, identity politics and government-run healthcare, even if it means ending private coverage that millions have and like.