Heavy hitters in Minnesota are bundling massive amounts of cash for President Obama's re-election battle, with a handful of well-known names raising more than $100,000 apiece, much of it to be spent elsewhere in the campaign's crucial final weeks.

Meanwhile, groups outside Minnesota are flooding the race between freshman Republican U.S. Rep. Chip Cravaack and DFL challenger Rick Nolan with so much cash that the Eighth Congressional District contest is fast becoming one of the most expensive in the country. So far, according to the Federal Election Commission, outside interests have spent more than $6 million, dwarfing what the candidates themselves have spent.

The cash provides the lifeblood for campaigns that have become pitched battles with uncertain outcomes. With just two weeks left before voters will decide, every day adds more pressure to spend the cash and bring the victory.

State Sen. Dick Cohen, Robert Pohlad and Gov. Mark Dayton's two sons, Eric and Andrew, each landed on a new list of bundlers released by the Obama campaign. All told, nine Minnesotans made Obama's list of donors who have bundled smaller donations into heaps of campaign lucre.

"It is kind of outsourcing your fundraising," said Richard Briffault, Columbia Law School professor of legislation.

The Romney campaign has not released a similar list.

Many of those presidential contributions have been spent elsewhere, but Minnesota is seeing more than its share of battleground spending in the fight for the U.S. House.

In the Eighth District joust between Nolan and Cravaack, the Democratic Congressional Campaign Committee has spent more than $1 million. The American Action Network, run by former Minnesota Sen. Norm Coleman, has spent more than $800,000 to keep Cravaack in office and reportedly will add $500,000 to that effort this week.

Two years ago, when Cravaack stunned the state by beating longtime Democratic Rep. Jim Oberstar, outside groups spent less than $500,000 to influence the election.

Cravaack supporter Steve Sjerven is not fond of the resulting ad barrage.

"I don't like all this money coming in from out of state," said Sjerven, of Cambridge.

Nolan supporter Joel Heller, of Duluth, is stunned by it.

"You can't turn on the channel without getting ads. ... Holy mackerel," he said.

Adding to the tsunami of spending: Supporters and opponents of the constitutional amendment to ban same-sex marriage have raised nearly $8 million. On Monday, New York City Mayor Michael Bloomberg announced that he would contribute $125,000 to oppose the Minnesota marriage amendment. Minnesota business people matched his donation, bringing Minnesotans United for All Families a one-day haul of a quarter of a million dollars.

In the presidential race, Minnesota is not a swing state, and so its status has been reduced to one of an ATM for Obama and Romney. The two men, along with Romney running mate Paul Ryan and Vice President Joe Biden's wife, Jill, all have held fundraisers here in recent months.

Some Minnesotans say they are pleased to play that role.

"I'm very supportive of President Obama. It is a way I can help," said Cohen, who, according to information the Obama campaign released, helped the president raise between $200,000 and $500,000. Cohen said he expects to raise more than $500,000 before the race is done. "Although I'm not a wealthy person myself," said Cohen, a St. Paul attorney, "I have the ability to get on the phone and talk to people."

Eric Dayton, the governor's son, said he was surprised his name appeared on the list. Although he and his brother Andrew hosted Obama at a fundraising dinner at their Minneapolis restaurant in June, he didn't expect he would be publicly credited as a bundler, he said.

Disclosing supporters who help raise presidential election funds is not legally required. But federal records show that Romney has cashed more than $2.6 million worth of Minnesota checks, much of that money coming around the time of the candidate's twin August fundraisers in Minnesota.

"You've written checks," Romney told a well-heeled crowd in Minnetonka Beach back then. "I need you now to go out and find somebody who voted for Barack Obama ... and convince them to join our team."

Staff writer Jennifer Brooks and the Associated Press contributed to this report. Rachel E. Stassen-Berger • Twitter: @rachelsb