RALEIGH, N.C. — “This is ground zero in America,” Republican National Committee Chairman Reince Priebus told a crowd of volunteers here at a rally for U.S. Senate candidate Thom Tillis.

Suburban moms in cardigans and dozens of North Carolina State frat boys applauded vigorously for Priebus’ digs at national Democrats and praise for Tillis, the speaker of the state House. Their cheers for the chairman’s call to oust Senate Majority Leader Harry Reid were rivaled in length only by the line for free barbecue after the speech.

“At the end of the day, we do this job because we believe in our own God-given freedoms. We believe in the Constitution,” Priebus continued, voice raised. “It’s up to us to save this country!”

It’s not rare for a party leader to cast an election in the sort of hyperbolic terms Priebus used last weekend. But with less than two weeks left until the midterm elections, it’s clear the Tar Heel State has indeed emerged as a ground zero — though not in the way the GOP chairman meant. The highly competitive Senate race in North Carolina is the multimillion-dollar epicenter of the negative campaigning that's come to characterize Election 2014 as the parties fight win tight races nationwide.

Despite a relatively low-cost local media market, more than $55 million in outside money has already been spent in North Carolina, and the race is expected to ultimately carry a $90 million price tag. This would make it far and away the most expensive Senate race in American history. While the state has been riven by local political controversies, largely because of actions the state legislature took under Tillis, the majority of TV ads in recent weeks have featured generic partisan arguments unconnected to local voter concerns. The outside groups pouring money into the state have done so with an eye toward the balance of power in the U.S. Senate.

The negative ads are as grating as they are pervasive. Voters in the state have been inundated with grainy video of Islamic State terrorists spliced with images of President Barack Obama and incumbent Democratic Sen. Kay Hagan, as well as attacks against Tillis over his positions on women’s health issues.

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According to the Center for Public Integrity, in the week between Oct. 14 and Oct. 20, North Carolinians saw 10,800 negative ads on the Senate campaign — or more than one negative ad per minute of television.

Even the candidates themselves have acknowledged how ugly things have gotten. On a crisp recent Friday afternoon at the state fair, Tillis joked with a supporter at the state party’s booth about the barrage of negative advertising, which has dismayed many Carolinians.

“I was watching an ad the other day, and I was, like, that man’s awful! Then I was, like, that man’s me!” Tillis said, before letting out a laugh and just minutes after he milked a cow for the cellphone cameras of a few political reporters.

Hagan has kept up a modest schedule of public events compared to other Democrats defending their seats in tough states. Both Tillis and Libertarian candidate Sean Haugh, who could win as much as 5 or 6 percent of the vote, appeared at the state fair in Raleigh on its opening weekend. Hagan did not. Local media reported that Hagan held a press conference at N.C. State on education that was closed to the public and included only 50 invited guests.

One reason Hagan did not have to be out on the campaign trail as aggressively this summer: Tillis did not resign from his position of speaker, which meant that when the state House session ran more than a month longer than usual, he could not devote as much time to the Senate race. So Hagan didn’t have to either. She enjoyed a static, though slim, polling lead throughout the summer, and wasn't until recently that her lead in some polls started to erode.

The negative campaigning is further poisoning an environment in the state where both Democrats and Republicans are deeply unpopular at all levels of government. A poll released this week by the Democratic-leaning, North Carolina-based Public Policy Polling showed that 52 percent of voters disapproved of Obama’s job performance and 50 percent disapproved of Hagan’s. At the same time, 49 percent held an unfavorable view of Tillis and 45 percent held an unfavorable view of the Republicans in the legislature he leads.

The race pits a Democratic incumbent so aware of her own electoral vulnerability that her tenure and reelection campaign have been cautious at best and reactive at worst against a Republican state leader who helped pass a slew of controversial laws. Tillis's legislature cut unemployment benefits, rejected the expansion of Medicaid under the Affordable Care Act and oversaw the enactment of restrictive voting laws, sparking regular protests by hundreds at the state Capitol.

Those “Moral Monday” protests could help protect key voting demographics, such as black voters, against the general sense of political fatigue being created by the millions in outside money being spent on negative ads in the state.

U.S. Senator Kay Hagan addresses a welcoming crowd and young campaign supporters at her campaign field office September 19, 2014 in Chapel Hill, N.C. Hagan was in Chapel Hill to rally her staffers and supporters from Orange and Durham counties to get out the vote against her opponent, NC House Speaker Thom Tillis in this November's election. (Harry Lynch/TNS/ZUMA Wire)

Political scientists for decades have believed that negative ads can depress voter turnout by fostering a pox-on-both-their-houses feeling among voters. But recent studies have complicated that view by suggesting that, at the very least, they work no better and no worse than positive ones. Researchers at George Washington University and Rutgers compiled data through 2006 and found that it was unclear that negative campaigns were more effective than positive ones in moving voters, even when they were more memorable.

“There is no consistent evidence in the research literature that negative political campaigning ‘works’ in achieving the electoral results that attackers desire,” the report in the Journal of Politics said. “Although attacks probably do undermine evaluations of the candidates they target, they usually bring evaluations of the attackers down even more, and the net effect on vote choice is nil.” Moreover, the research found that the overall “darker public mood” that can be created by negative ads “may be due more to coverage of negative ads in the media rather than the ads themselves.”

Outside observers tracking the North Carolina race still believe key demographics will show up to the polls, despite the repellent negative ads.

"Black voters are more likely to be energized than not. The Moral Monday movement that’s been taking place in North Carolina has been very heartening to a lot of people. It’s energized a lot of people,” said David Bositis, a senior research associate at the Joint Center for Political and Economic Studies. “There’s a lot of anger about what the state Legislature has done, including the voter ID laws. ... There certainly are reasons for black voters in North Carolina to turn out.”

Bositis also pointed to the infrastructure created by Obama’s victorious 2008 campaign here and how it could help to target the voters needed to push Hagan to a victory.

But in 2012 Obama lost the state, and the pro-Democratic wave that swept Hagan into office in 2008, at least nationally, is a thing of the past. Democrats hope that the unpopularity of local Republicans and the maneuverings of the state legislature, which they call extreme, could turn out the Democratic vote for state and county-level officials and, in turn, save Hagan’s seat.

Indyweek, the independent newsweekly for the triangle region that includes Raleigh, Durham and Chapel Hill, identified one particular race—the Wake County commissioners election—as crucial in deciding the region’s future. The region is among the fastest-growing areas in the country and has the potential to be as influential in the state in future elections as Northern Virginia has become in Virginia.

North Carolina House Speaker Thom Tillis speaks at a rally at the Buncombe County Republican headquarters in Asheville, N.C., on August 29, 2014. (Chuck Burton/AP Photo)

“You always think of coattails coming from the top-down. I think Wake County is going to be one of those cases where there’s going to be [a] push up,” said state Sen. Mike Woodard, a Democrat, at a candidates forum last weekend in a Durham mosque. “That county commissioners race is going to be very important in affecting legislative races and the U.S. Senate race, because I think you’ve got the potential there to throw out four incumbents and bring in four Democratic challengers and people are excited for that race.”

But Carolinians seem weary. They appear to be more excited about Nov. 5 and the election being over than about the outcome of the Senate race itself.

Even a top Tar Heel tobacco lobbyist told Yahoo News at the state fair that he is tired of the negative ads.

“I think everyone out here, rank and file, in North Carolina, are tired of the negativity — even though I know it’s effective,” said Graham Boyd, the executive vice president of the North Carolina Tobacco Growers Association, who stood outside the “Tobacco Barn” at the state fair as Tillis, whom he calls a “personal friend,” hung tobacco leaves from the barn’s rafters.

“Golly, we watched a program over the weekend, and I said to my wife, 'There’s more Hagan and Tillis in a 60-minute show ... than there was the actual program,'” he said. “It really kind of gnaws you after a while. ... We’re ready for Nov. 4 just to end it.”