Congressman Kevin Cramer, a folksy, white-haired Republican running for US Senate, was waiting in cargo shorts and a polo for a small-town North Dakota parade to begin. Standing next to a pickup truck and a knot of campaign volunteers—all clad in the same “Cramer Crew” T-shirt—he told them he couldn’t do it without them.

Fuglie’s prediction might be an unremarkable sum for other Senate races, but ad money goes further in the Peace Garden State, population 755,000—not much bigger, by headcount, than the city of Seattle. It’s a sprawling state, full of prairie and foothills and oil fields, but so sparsely populated that it can have a small-town feel: Bismarck residents might pass the attorney general in the grocery store.

“It’s going to be fucking nasty. There’s going to be $50 million here,” said Jim Fuglie, a former director of the state’s Democratic Party affiliate turned blogger. Political ads will air so frequently, he joked, that “you won’t see any medicine ads on the six o’clock news anymore.”

But it represents today’s battle in North Dakota's hard-fought campaign for the Senate, a race that could determine which party controls the entire chamber. The Senate is currently split 51–49, and every seat on the ballot this November could be the one that changes everything. North Dakota’s race is an unusually close contest between two of the state’s heavyweights: Cramer, its lone congressman, and incumbent Democratic Senator Heidi Heitkamp. It’s poised to swing money and attention like a fist into one of the quietest corners of America, and in a state that prides itself on polite, Midwestern gentility, observers are already bracing for an influx of outside cash and acrimony.

Storm clouds were passing, and the sun was about to shine. Moments later, the parade stepped off through Valley City, a town of about 6,500. Cramer and company tossed the crowd Skittles and Starbursts out of plastic buckets. Speakers on the pickup blared country. To an outsider, the production might hold the local charm of a rural state representative’s contest.

A close ally of Donald Trump, Cramer brags that he’s running at the encouragement of the president, who visited Fargo late last month. He voted to repeal and replace the Affordable Care Act and supported the GOP’s tax overhaul. Heitkamp has bucked both those policies, but has voted with Trump elsewhere, including on Gina Haspel’s appointment to lead the CIA; she even cut an ad touting her Trump-friendly record. It’s an unsurprising move in a state that supported Trump over Hillary Clinton by a margin of more than two to one—and where Heitkamp was elected in 2012 by less than 1 percent of the vote.

North Dakotans are familiar with hardball politics, having watched a tough GOP gubernatorial primary two years ago and the 2012 race that first sent Heitkamp to Washington. But this race is already showing the signs of a hard-fought contest, and as Mike McFeely, a columnist for the Fargo Forum, put it in February: “Buckle up, North Dakota. The political campaign of your life is about to begin.”

The race began in earnest in February, when Cramer—after briefly saying he wouldn’t run—reversed course and jumped in. Besides the standard, constant messaging around both candidates and their track records, the campaign has already seen the flashes of fighting that portend a big race. The state’s Democratic Party affiliate has criticized Cramer’s payments to himself and family members with campaign funds—like for his wife’s work as campaign manager—which they call unethical. In one of the odder exchanges of this past year, they circulated a Valentine’s Day poem about it: “Roses are red, nepotism is icky; Cramer paying his family is morally sticky.” On Facebook, this message came with an image of Cramer against a pink background with white hearts. (The Democratic candidate for attorney general has gone so far as to accuse Cramer of corruption for his campaign finances, including some of this year’s high-mileage reimbursements to himself and his wife, though an AP fact check rates those payments as reasonable.) Cramer has denied wrongdoing.

“I think that this is likely to be the most expensive race, per vote, in American history."

The National Republican Senate Committee, for its part, has hammered Heitkamp on an apparent moment of levity with Senate Minority Leader Chuck Schumer after she voted against an abortion ban. After the Senate Leadership Fund questioned her foreign policy judgement in an ad featuring ailing Syrian children, Heitkamp took to Twitter: “Using poisoned, dead Syrian children in a political attack ad is disgusting, shameful and downright wrong," she wrote.