By Jim Morrill, The Charlotte Observer (MCT)

CHARLOTTE, N.C. — From the Koch brothers and Art Pope to George Soros and Michael Bloomberg, wealthy donors are making North Carolina’s U.S. Senate race one of America’s first $100 million contests.

Outside groups continue to flood the state with ads and accusations, forcing Democratic U.S. Sen. Kay Hagan and Republican Thom Tillis to keep scrambling for dollars in the campaign’s final two weeks.

Money spent or committed in the race is poised to top $103 million, according to public records and interviews with donors. Three-quarters of it comes from party and interest groups. More than $22 million is “dark money” from groups that don’t disclose their donors.

The flood of money paid for nearly 80,000 TV ads through Oct. 13, according to a Center for Public Integrity analysis of CMAG/Kantar Media tracking data. At one point this month, that translated to three Senate ads every five minutes.

And more are coming. On Friday, a conservative group announced a new $1 million TV campaign against Hagan, who responded with her own new ad.

The figures may understate actual spending.

Campaigns and their allies are also spending online and on the ground as they try to mobilize voters in a race that could help determine control of the Senate.

Campaign spending has exploded since the U.S. Supreme Court’s 2010 Citizens United ruling, which opened the door to more money from corporations and labor unions. Critics say that gives wealthy donors a disproportionate voice.

“The most affluent donors are calling the shots,” says Sheila Krumholz, executive director of the Center for Responsive Politics. “They’re picking races to target … that offer an opportunity to flip the Senate and therefore shift the balance of power in Washington. …

“Unfortunately what that means for voters is they’re feeling even less relevant than they otherwise would.”

Spending continues to rise as polls show the race tightening. As an incumbent, Hagan has long enjoyed a significant fundraising advantage. Reports filed last week with the Federal Election Commission show she raised $21.6 million through September to Tillis’ $8.2 million.

As a result, Tillis’ campaign has spent just $6 million. But outside groups have supplemented that.

Together they’re spending $42.8 million on his behalf, according to an Observer analysis. Almost half of that is so-called dark money from political nonprofits such as Carolina Rising, a Raleigh-based group launched in April.

The National Republican Senatorial Committee is spending more than $10 million for Tillis. An additional $10.5 million has come from groups funded by Charles and David Koch, conservative industrialists from Wichita, Kan. Nearly $6 million has come from two groups tied to former White House adviser Karl Rove.

Hagan’s campaign has spent $19.6 million, more than half in the past quarter. Outside groups have contributed nearly $35 million.

Her biggest supporter — and the biggest player in the race — is the Democratic Senatorial Campaign Committee. It’s putting up at least $17 million.

Only $2.3 million of her outside money has come from dark money groups. But a lot has come from groups funded by some of the nation’s wealthiest donors.

The Senate Majority PAC, for example, has spent more than $10 million on TV ads for Hagan. The PAC, tied to Majority Leader Harry Reid of Nevada, whose leadership job is on the line if Democrats lose the Senate, appears to have spent almost a third of all its resources in North Carolina.

Donors to the Democratic Super PAC include Chicago media executive Fred Eychaner and San Francisco billionaire and environmental activist Thomas Steyer. They’ve each given the PAC $5 million. Steyer’s own Super PAC, NextGen Climate Action, contributed to the League of Conservation Voters, which also helped Hagan.

Hagan’s allies include at least three dark money groups and donors, according to published reports. Donors to Patriot Majority USA, for instance, include a group called America Votes. According to the Center for Public Integrity, donors to that group include billionaire investor George Soros.

Those wouldn’t be the only groups fueled by wealthy donors. Bloomberg, the former New York mayor, gave $2 million to Women Vote!, a group backing Hagan. And Raleigh businessman Art Pope gave $400,000 to Freedom Partners Action Fund, a Super PAC backed by the Kochs.

“This is going to be a new record year for outside spending,” says Ian Vandwalker, a lawyer with the Brennan Center for Justice at NYU law school.

“North Carolina is from what we’ve seen the biggest target. It’s probably going to be the biggest Senate race ever in terms of outside spending.”

It’s certain to be one of the most expensive Senate races ever. Massachusetts’ 2012 race between Democrat Elizabeth Warren and Republican Scott Brown cost at least $76 million.

It is certain to be North Carolina’s costliest race. For a long time, the 1984 contest between Republican Sen. Jesse Helms and Democratic Gov. Jim Hunt was the state’s most expensive. It cost $26 million at the time. That’s $60 million in today’s dollars.

For weeks Hagan blasted Tillis, the state House speaker, with TV ads criticizing his record on education. Last month, outside money helped Tillis balance the airwaves, according to an analysis by the Center for Public Integrity.

After trailing her and her allies for month, Tillis ran more ads the final two weeks of September. In the first week of October Hagan and her backers were on top again with 4,579 ads to 3,328 for Tillis.

Marc Rotterman, a Republican media strategist, says recent ads about a controversial business deal involving Hagan’s husband could have influenced some voters. But generally he says most people have made up their minds.

“At the end of the day it’s still going to come down to turnout,” he says. “It’s find ’em, vote ’em, count ’em.”

Photo: Mr T in DC via Flickr