Kalispell, Montana (CNN) The acoustic song is folksy and gentle, carrying the sort of ease you'd expect from a quaint Montana event.

Singing without a microphone and strumming his guitar is Rob Quist, crooning his campaign theme song: "If you stand with me, I can stand up for you."

A woman in the Kalispell, Montana, home, packed with several dozen people to meet Quist at this political meet-and-greet, sways to the tune.

This is hardly the sort of pounding political anthem for an insurgent run at Montana's at-large congressional district seat, recently vacated by Ryan Zinke, now interior secretary in the Trump administration.

The Big Sky state, where President Donald Trump soared to victory by more than 20%, is solidly Republican red, and Democrats haven't managed to snag the state's lone House seat in almost 20 years.

"And then, the Democrats picked a unique outsider candidate. A home-grown, musical star in Montana who ... kind of came out of nowhere," said Lee Banville, associate professor of journalism at the University of Montana.

Banville, who specializes in the intersection of politics and media, says in Quist, 69, Democrats have found a candidate who grew up in the humble town of Cut Bank, Montana, turned himself into a state-wide celebrity with his poetry and banjo and whose name has been well-known to locals for decades.

Add in an anti-Trump fervor among the Democratic base after a strong showing in Georgia's 6th Congressional District and $2.5 million in contributions have begun flowing into Quist's campaign.

"There is some momentum on the Quist side," Banville said.

Like his campaign song, Quist appears more Montana rancher than Washington lawmaker, and that is where a potential upset brews in a state that re-elected Democratic Gov. Steve Bullock and Sen. Jon Tester, another Democrat.

They're both politicians who have found ways to connect with their majority-Republican electorate -- which Quist already authentically resembles. As he has throughout his musical career, Quist dons his cowboy hat, boots and belt buckle at public events. He approaches supporters with quintessential Big Sky ease, hammering his pet policy, public use of waterways and land.

Traveling to campaign events that span the entire state for the at-large congressional race, Quist rides in a small RV, driven by one of his band members.

"This is about Montana values," said Quist. "We have a lot of common ground and that's where I'm hoping to connect with the people of Montana, where we can put this party ideology aside."

As he talks about the commonality of Montana people, Quist also admits for him to win: "It's going to be a challenge."

Recent history suggests it may be significantly more of a challenge, simply by looking at the congressmen who have represented Montana. Democrats have lost the last 11 congressional elections, the longest losing streak for Democrats for any statewide office since 1889. But this special election is more unusual than others.

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National Democrats are seeing a revitalized base after Democrat Jon Ossoff nearly scored an outright win in a heavily conservative House district in Georgia last month and a better-than-expected performance in a special House election in Kansas earlier in April.

The Quist campaign says it has received $2.5 million in contributions, with an average donation of $32 or less. Those factors hover over Montana, Banville said, as does "a healthy dose of anti-Trump sentiment."

Independent voter Jill Weiser, who says she has voted both for both Republicans and Democrats, came to listen to Quist speak, driven by her disgust with the President. "Donald Trump has me so outraged that I feel like I've been slapped in the face," said Weiser. "I'm voting with great vigor rather than a feeling that I'm voting because you're supposed to."

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On May 25, the date of the special election, Trump may drive a Democratic base to Montana polls, but the GOP believes the President only helps their candidate, Greg Gianforte.

Gianforte, a businessman who made millions when he sold his tech company to Oracle, recently welcomed Donald Trump Jr. at his campaign event.

"The Trump train is chugging along in Montana," Gianforte said. "I look forward to being a voice for Montana and working with Donald Trump to affect those changes."

If Quist is quirky, Gianforte is traditionally a western Republican. He poses at gun shows with supporters and talks about Obamacare being a failure. His stump speech rails on federal government overreach and high taxes. On his own wealth, Gianforte said: "I'm a fan of prosperity. And I think as I talk to Montanans, they want prosperity too."

Linda Holden, a longtime GOP voter and musician, said she's known Quist for many years, but she's known his music for decades.

"I think he's very personable and he's a very good entertainer," Holden said. "I'm going to vote for Greg."

Gianforte says he feels "encouraged" about a victory on May 25, but he won't go so far as to say confident.

Instead, he repeated a canned line about his opponent several times in an interview with CNN: "He's Nancy Pelosi in a cowboy hat."

The mud has also been flying in a series of campaign ads running on television.

GOP-funded ads claim Quist wants a national gun registry, something Quist denies. Quist said he would like to limit fully automatic rifles but strongly supports the 2nd Amendment, rolling out his own ad showing him shooting the negative GOP ad with his family's rifle.

The Washington Free Beacon posted a report that Quist performed at a nudist colony.

Quist confirmed to CNN that he did -- but that he performed completely clothed. Quist added that he performs for a wide variety of groups, including Republican events.

Banville said he believes that the mudslinging suggests state Republicans are worried about Quist's momentum, understanding that to win statewide in Montana, being "Montanan" can be more important than party affiliation.

And then there's the question of Montanan likability, the unknown and powerful variable in the Big Sky state.

"Montanans are much more likely to want to hang out and vote for the guy with the banjo than the guy who made millions of dollars in software," Banville said.