Bernie Sanders on Tuesday narrowly edged out Pete Buttigieg in a nail-biting New Hampshire primary — winning in a razor-thin victory in the Granite State after the chaotic Iowa caucuses, according to ABC, NBC and CBS network projections.

The self-described “Democratic Socialist” and party outsider from Vermont won 26 per cent of the vote but failed to turn out a revolution in his New England neighbourhood and shake Buttigieg after they virtually tied in Iowa.

“The reason that we won this tonight in New Hampshire and we won in Iowa is our volunteers,” said a jubilant Sanders.

“We have an unprecedented grassroots movement from coast to coast. We are putting together a multi-gender, multiracial political movement. This is the movement from coast to coast that we finally have an economy and a government that works for all of us,” New York Post quoted Sanders as saying.

Earlier in the month, Sanders held a narrow lead among the Democratic contenders. “I think he’s a communist,” said Trump, for whom name-calling and character smearing are an integral part of his campaign for re-election in November this year.

Earlier, voters in the midwestern state of Iowa participate in the long process that will eventually choose the Democratic party’s presidential nominee, who will take on Donald Trump in November’s US Presidential election.

The primaries and caucuses are a series of contests, in all 50 US states plus Washington DC and outlying territories, by which each party selects its presidential nominee.

On January 22, former US secretary of state Hillary Clinton had launched a scathing attack on a presidential hopeful and 2016 Democratic rival Sanders, telling a documentary that “nobody likes him.”

Sanders, 78, pushed Clinton to the wire four years ago in an acrimonious, months-long battle for the party’s nomination. Clinton won that race but lost to Trump in November.

Sanders was treated for a blocked artery after experiencing chest discomfort and has cancelled campaign events until further notice.

Sanders is the oldest candidate vying to take on President Donald Trump, 73, and is third in the Democratic nominee polls behind Joe Biden, 76, and Elizabeth Warren, 70.