Video report by ITV News Washington Correspondent Robert Moore
The race to be the next US President could reach a defining moment in the next few hours.
Democrat party members have been casting their vote in New Hampshire, on who they want to take on Donald Trump in November.
The candidates will find out later on whether they are still in the fight - or whether momentum is slipping away.
The senior senator, Bernie Sanders, will find out shortly whether his campaign are still in the fight, in with a decent chance.
Whoever ends up in the lead, party organisers are hoping there is no repeat of the counting chaos last week in Iowa.
Describing Sanders, ITV News Washington Correspondent Robert Moore said: "He is the rarest of American politicians, a self-declared Democratic socialist."
At 78 years old, Sanders is also the oldest candidate in the race but paradoxically his greatest appeal is the young, millennial voters.
He told reporters earlier: "I think you're seeing this all over the country, there's an involvement as young people get increasingly involved into the political process, they are worried about climate change, they are worried about racism and sexism and homophobia, they are worried."
But Sanders has rivals everywhere he looks.
Tuesday’s contest comes just eight days after Iowa caucuses injected chaos into the race and failed to report a clear winner.
While Bernie Sanders marches forward, moderates are struggling to unite behind a candidate.
After essentially tying with Sanders for first place in Iowa, Pete Buttigieg, the 38-year-old former mayor of South Bend, Indiana, began his day as the centrist front-runner.
But hundreds of others were queuing for another political show in New Hampshire, the great disrupter, the US President himself trying to steal headlines in New Hampshire, practising his attack lines for any other democrats who may emerge as his eventual competitor.
Trump said: "We are going to defeat the radicals, socialists, democrats, we are going to win New Hampshire in a landslide."
During the final day of campaigning, many voters said they were still struggling to make a choice.
Betty-Joy Roy, a 64-year-old director of activities at an assisted living facility in Manchester, said she only decided on Monday to vote for Sanders.
"I’m sick of politics as we know it, and I’m ready for someone who can do something," she said.
She added: "It was between him and Biden. I was having a hard time but I think we need a change."