In below freezing temperatures, the line to see Pete Buttigieg in Nashua, New Hampshire stretched out from the gym doors at Elm Street Middle School. Down the block, the line snaked around the corner, then around yet another corner.

The turnout was a testament to the newfound celebrity of the candidate, a former mayor of a mid-sized city in Indiana who, just a year ago, virtually nobody in America even knew existed.

But they certainly know him now. Just at the start of the 2020 primary process, Mayor Pete – as many like to call him, due to his tongue twister of a last name – has shown that in American politics, no candidate is inevitable.

Instead, a 38-year-old newcomer to national politics can seemingly topple the candidate folks thought was unstoppable, and head into the nation's first primary as a front-runner and candidate just about everyone is talking about. That quick rise in political fortunes does not seem lost on him.

"I know how seriously voters here in New Hampshire take that responsibility, that influence, that thumb on the scale that you've got," Mr Buttigieg told the crowd on Sunday. "In the New Hampshire tradition that had a lot of you in the summer and the fall coming to my events and hearing me out and at the end saying, 'You know, that was pretty good. I think you're in my top seven now.'"

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Mr Buttigieg heads into the Tuesday primary on the heels of a strong performance in Iowa, when voters came together last week for the bizarre spectacle that is the state's caucuses.

While the reported results from that contest have been criticised for inconsistencies and muddled reporting that took days before a full account was released publicly, Mr Buttigieg's status as a front-runner out of the state alongside Vermont senator Bernie Sanders is uncontestable – even if he was criticised for seeming to claim victory far too early.

The former midwestern mayor now finds himself ahead of the former vice president, Joe Biden, who once seemed like the obvious choice for moderate Democrats seeking to find a candidate with a vision that can win a Democratic nomination in a cycle marked for a surging progressive sentiment, while avoiding the kinds of policies and labels like "socialist" that some view as a liability for Mr Sanders should he face off against Donald Trump.

Pete Buttigieg poses for selfies with supporters while campaigning at Dover Middle School in New Hampshire (EPA)

"I'm 98 per cent sure that I'm voting for Pete at this point," said Mary Rioux, 42, of Manchester.

Ms Rioux said she made her decision just after the CNN town hall late last week. Still, she said she also likes Amy Klobuchar quite a bit.

Mr Buttigieg still faces several notable obstacles on his path to the Democratic nomination. At 38, he is the youngest candidate in the field, a potential liability that is underscored by the fact that his highest elected office sits several rungs down from some of his most prominent opponents.

On Sunday, Mr Buttigieg was introduced by Nashua's mayor and himself recognised that fact, but cast his distance from Washington as a political strength in spite of the brutal attack ads placed by Mr Biden, mockingly comparing his experience as vice-president with the kind of decisions Mayor Pete made in South Bend, like whether to put colourful lights underneath a bridge or whether to change pet chip regulations.

"I'm so glad to have the support of a fellow mayor at a time like this. Remember, mayors have to get things done. You're never gonna hear of a city government shutting down because two parties don't agree. We just have to make sure that the water keeps flowing through your taps so we figure it out," Mr Buttigieg said.

"We need to make Washington look like our best run cities and towns, instead of the other way around," he said.

Still, Jamie Bourgeouis, a 43-year-old Nashua voter, said that Mr Buttigieg seems like a sensible choice heading into 2020. She said he's not quite as progressive as she might like, but that he might do the trick.

"I don't know who I'm voting for yet, but I like Pete," she said. "I'm torn on who to vote for. I want someone who can beat Trump. So, I'll probably go for someone who's a bit away from my personal politics."

Days before the primary, Mr Buttigieg trails Mr Sanders in aggregates of polls, with 21.3 per cent support in the state compared to the Vermont senator's 26.1 per cent. Eight points below that is Elizabeth Warren, the Massachusetts senator who came in third place in Iowa and is seeking a strong showing in New Hampshire, where she has focused a considerable ground game.

And so, before he can begin counting his chickens, Mr Buttigieg must prove himself in the Granite State, where voters like to tout their sense of independence, and many say they don't really care what Iowa had to say about the candidates – they want folks like Mr Buttigieg to prove they're the right choice again.

How to pronounce Buttigieg

"I'm just here evaluating," Carl Dubois, a 48-year-old voter from Hudson, New Hampshire, said outside of the event. He said he planned on seeing Mr Biden and Amy Klobuchar before making a final decision. "I wasn't really paying attention to the Iowa caucuses. I don't really engage until New Hampshire."