Minnesota’s Eighth Congressional District has become a money magnet in the 2014 election, drawing more than $12 million to the contentious race between Democratic Rep. Rick Nolan and his Republican challenger, Stewart Mills.

The bulk of that, nearly $9 million, has come from outside groups as they attempt to influence the outcome of the race.

The biggest players so far have been the Democratic Congressional Campaign Committee, which has spent $3 million, followed by the National Republican Congressional Committee, at $2.4 million.

Other sizable spenders include the U.S. Chamber of Commerce, which has poured $800,000 into the district, and the American Action Network, a center-right group led by former Sen. Norm Coleman, which has spent more than $300,000. On the left, the Democrats’ House Majority PAC has spent $1 million, while unions have popped for more than $300,000.

The result of all the cash is that television viewers in the Eighth could see more than 100 ads in the district in the final week, as well as dozens more for the Senate, governor and down-ticket races, from supporters and the candidates. So many ads are flooding the airwaves in northern Minnesota that television stations are boosting the cost of airtime.

The outside money has largely gone to tear down Nolan and Mills. According to public data, groups have spent $4 million to oppose Mills and almost $3.5 million to oppose Nolan.

The Rothenberg Political Report recently changed its rating of the race from “Lean Democrat” to “Toss-up/Tilt Democrat,” a sign that Mills is making the race tough for Nolan. (A third candidate, Ray “Skip” Sandman of the Green Party, is also running.)

As of the last report, due to the Federal Election Commission on Thursday, Nolan had raised more cash from donors than Mills had, but Mills had spent more. In addition to the $1.5 million he has raised, Mills, a scion of the Mills Fleet Farm family, has invested $325,000 into his campaign. Nolan has brought in nearly $1.9 million from donors.

Although they both raised a little more than $120,000 during the first two weeks of October, Nolan had more cash left in the bank. The incumbent had about $380,000 left to spend, while Mills had a little under $200,000.

Incumbents having a cash advantage is a theme across all of the closely watched races in Minnesota. Democratic U.S. Sen. Al Franken had $2.8 million stocked away for the final weeks, three times the cash on hand that challenger Mike McFadden had. In the Seventh Congressional District in western Minnesota, Democratic Rep. Collin Peterson had $520,000 in cash as of last week, compared with GOP challenger Torrey Westrom’s $184,000.