MANCHESTER, N.H. – New Hampshire’s presidential primary kicked off at midnight – as voters in three tiny townships in the state’s North Country and White Mountains cast the first ballots in the first primary in the White House race.

Dixville Notch – which has held the midnight voting tradition for 60 years – as well as nearby Millsfield and Hart’s Location, grab the national spotlight every four years as they report the first results in New Hampshire.

In Dixville Notch, a surprise candidate came away the winner. Former New York City Mayor Michael Bloomberg, who did not campaign in the state, scored three write-in votes, followed by a vote each for former South Bend, Ind., Mayor Pete Buttigieg and Vermont Sen. Bernie Sanders. Minnesota Sen. Amy Klobuchar came out ahead in the other two locations.

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On the final day before the primary, meanwhile, Sen. Sanders emphasized to supporters that “what happens here in New Hampshire is enormously important...the whole country is not only looking at New Hampshire - in fact, the whole world is looking at New Hampshire.”

The populist senator from Vermont who’s making his second straight White House run is in the driver’s seat – sitting atop the final public opinion polls, drawing large and energetic crowds in the closing days, and sporting arguably the largest grassroots get-out-the-vote operation in the Granite State.

After getting out of Iowa’s caucuses with essentially a tie with 2020 nomination rival Buttigieg, expectations are high for Sanders in a state where he shares home-field advantage with fellow progressive standard-bearer Sen. Elizabeth Warren of Massachusetts.

As he did in Iowa, Sanders is stressing to his supporters that “if we have the highest voter turnout in New Hampshire primary history, I am confident that we are going to win here in New Hampshire and if we win here in New Hampshire, we're going to set the pace to win Nevada and South Carolina and California.”

But meeting expectations in a state where he crushed eventual nominee Hillary Clinton four years ago is crucial for Sanders.

Sanders closed out his bid in the first primary state with a massive rally and concert that drew over 7,500 to the University of New Hampshire at Durham - which was by far the largest crowd for any Democratic presidential candidate in New Hampshire this cycle.

He was joined by Rep. Alexandria Ocasio-Cortez and a bunch of other high profile surrogates.

“New Hampshire remains Bernie’s to lose. He dominated in 2016 and his coalition seems confident again. That said, if he doesn’t win, it’s a huge hit to the Sanders path,” emphasized longtime Democratic strategist Sean Downey, a national adviser on Sen. Cory Booker of New Jersey’s now-defunct 2020 presidential bid and a veteran of numerous political campaigns in New Hampshire.’

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Sanders declared victory in Iowa – where the results dribbled in for days after a reporting debacle on caucus night – by pointing to his lead in the raw vote totals coming out of the caucus precinct sites.

Buttigieg --the former South Bend, Indiana mayor -- also claimed victory, spotlighting his narrow edge in the percentage of state delegates won. And for Buttigieg – like Sanders – a strong finish in New Hampshire is vital for his hopes of capturing the nomination.

Buttigieg was also stressing the importance of the primary, telling supporters the eve of the primary that Tuesday will be a “historic night that will set the course for the party and the rest of the world. We are lucky and unlucky enough to be in a point of history where it will be recorded what we did.”

The 38-year old candidate – the youngest in the field – told supporters on the primary eve that Tuesday will be a "historic night that will set the course for the party and the rest of the world."

Buttigieg closed in on Sanders in the polls in the days after the Iowa caucuses. But one of the two tracking polls suggested that the candidate saw his numbers drop over the weekend. That wasn’t reflected on the campaign trail, as Buttigieg drew more than 5,000 people to his events on Sunday.

Buttigieg has struggled to resonate with African American and Latino voters. And with the White House race moving next to Nevada and South Carolina – which have much more diverse electorates – a strong finish in New Hampshire is paramount for Buttigieg.

Pointing to the calendar ahead, Downey emphasized that “Mayor Pete’s situation here is urgent given his real lack of traction in the south and out west.”

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Illustrating the tension between the top two contenders, Buttigieg once again took aim at Sanders on Monday, saying that “at a moment when our country is so divided we can't risk further polarizing the American people. That's why I'm very concerned about the suggestion that either you got to be for revolution, or you must be for the status quo because that vision of politics as all or nothing is a vision that most of us can't see where we fit in.”

Sanders – who’s funding his massive campaign war chest through small-dollar grassroots donation – took jabs at Buttigieg and former Vice President Joe Biden – saying they “have dozens and dozens of billionaires contributing to their campaigns.”

The former vice president’s message on Monday night to his supporters: “stick with me 24 hours and we’re going to be just fine. We’re going to win this nomination.”

Biden’s said he’s not “writing off” New Hampshire– but it sure looks like he’s lowering expectations.

“I took a hit in Iowa and I’m probably going to take a hit here,” Biden said in a striking moment at the top of Friday night’s prime-time Democratic presidential nomination debate.

Asked the next day by Fox News if he was writing off the Granite State, the former vice president fired back, saying, “I’m not writing off New Hampshire. I’m going to campaign like hell here in New Hampshire, as I’m going to do in Nevada, in South Carolina and beyond. Look, this is just getting going here. This is a marathon.”

For Biden, however, at least a third-place finish here could be critical, if only to prevent an exodus of donors and the possible erosion of his so-called "firewall" of support in the looming South Carolina contest. With the race for first increasingly looking to be between Sanders and Buttigieg, Biden’s essentially battling with Warren and Sen. Amy Klobuchar of Minnesota for a top-three ticket out of the Granite State.

It's a stunning predicament for the candidate who was once the unrivaled front-runner for the nomination. He's long made electability central to his campaign pitch. But University of New Hampshire pollster Andrew Smith highlighted that the final UNH tracking poll for CNN – conducted after Biden’s lackluster fourth-place finish in the Iowa caucuses, indicate that “Bernie Sanders is seen as the most electable candidate” to take on Republican President Donald Trump in November’s general election.

“If your candidacy is based on electability, once you don’t win elections, that electability argument dissipates very rapidly,” Smith explained, “If Biden does very poorly in New Hampshire, going forward those voters in Nevada and South Carolina are going to look at that electability argument in a very different light because to be electable, you need to win elections.”

Warren – once a co-frontrunner in the nomination race - is also under the spotlight. She faced a deluge of questions the past couple of days from reporters asking how crucial a strong finish in New Hampshire is to her White House bid

“I didn't start by doing polls a year ago, and I still don't do polls,” responded the senator, who famously avoids all talk of her position in the polls.

Warren – who’s repeatedly avoided saying New Hampshire’s a “must-win” state, has emphasized that “the way I see this is it’s going to be a long campaign…we’ve built a campaign to go the distance.”

Talking to reporters on her campaign’s press bus on Monday, the candidate told reporters “I've been counted down and out for much of my life.”

But she emphasized that “you get knocked down, you get back up. And you keep fighting because it's not about me, it's about the people who are counting on me.”

Downey noted that “with a full field, the difference between third and fourth could be a few points and I’d look to strong organizing game and surrogate operations from Warren and Biden to make things interesting.”

But thanks to a last-minute surge, add Klobuchar to the mix in the fight for third place.

Klobuchar touted on Monday that “as you probably heard we’re on a bit of a surge. I woke up this morning to find out that we are third in two polls.”

One of the two final surveys – a Suffolk University tracking poll for the Boston Globe and WBZ – suggested that Klobuchar soared nine percentage points over the past two days.

But the big question is whether Klobuchar can capitalize on her late tide of momentum.

Smith cautioned that “I don’t think though that Klobuchar’s going to have the organization necessary to take advantage of her debate performance and her performance in Iowa and get those people out to vote. She doesn’t have anywhere near the on-the-ground organization as the other top candidates.”

Adding to the uncertainty ahead of the primary results – the fact that Granite Staters are traditionally late deciders. The final polls illustrate the point – showing that nearly half of those who are currently backing a candidate suggested that they could change their minds before they vote.

Smith gauged that “I would see, easily 15-20% of New Hampshire Democrats making up their mind on primary day.”

And Downey said “I can’t stress this enough. New Hampshire likes underdogs and will decide late. This race isn’t over.”

Fox News' Kelly Phares, Tara Prindiville, Andrew Craft, Andres del Aguilla, and Madeleine Rivera contributed to this report