As Minnesota's candidates for governor head into the final weeks of the campaign, they find themselves outgunned on TV -- but not by each other.

Interest groups have become the new power players in political ads.

The Alliance for a Better Minnesota, a liberal coalition, has saturated the airwaves with more than $1 million in post-primary ads that go after GOP candidate Tom Emmer. Business-backed Minnesota Future and MN Forward have each spent more than $300,000 on ads that either promote Emmer or take off on his DFL opponent, Mark Dayton. That's nearly $1.8 million in the last month.

By comparison, ad buys by the candidates have been relatively paltry -- just $430,000 among Emmer, Dayton and Independence Party candidate Tom Horner in the Twin Cities market.

To bring an infusion of cash that's under their control, candidates have turned to a slew of famous faces. Politicos lending their star power to the race this week include Louisiana Gov. Bobby Jindal, former President Bill Clinton and former Gov. Arne Carlson. Each appearance is aimed at fueling campaign war chests and rallying the base.

"This is when you put on the big push so that you're fully funded going into the final six weeks of the race," said Brian McClung, who helped run Gov. Tim Pawlenty's 2006 reelection bid and who now heads MN Forward.

Jindal traveled to Minneapolis on Monday night for a $1,000-per-plate-and-up fundraiser at the Minneapolis Hilton for Emmer.

Dayton will follow with a Clinton fundraiser on Tuesday evening that will bring in at least $250 per person. The fundraising goal? "Whatever we can manage to raise within the laws of the state of Minnesota," said Dayton, who is bringing Vice President Joe Biden in early next month.

Horner countered those names with his own on Monday: former two-term Gov. Arne Carlson. The campaign announced it had snagged the veteran Republican's endorsement Monday morning, and Horner spent a full day showing Carlson off before a planned fundraiser in Edina to bring in some much-needed cash.

"I don't want to sit on the sidelines," Carlson said. "I told Tom Horner I'll go anywhere, anytime."

Ad wars

Records at Twin Cities television stations show Emmer has far outspent his opponents on the airwaves since the primary, paying about $250,000 to run one biographical ad. Dayton has spent about $115,000, while Horner has spent $63,000. Those figures do not account for ads in greater Minnesota.

Those amounts would be respectable in previous governor's races, but have put candidates far behind independent groups. A recent U.S. Supreme Court decision lifted campaign spending restrictions on corporations, giving birth to such groups as MN Forward and Minnesota's Future.

According to Denise Cardinal, executive director of the union-backed Alliance for a Better Minnesota, the group has purchased $1.15 million in anti-Emmer ads in the past month. McClung said MN Forward bought $300,000 of TV time across the state in the same period. Minnesota Future has also been busily purchasing airtime.

The full amount spent by issue-advocacy groups may not be known for some time. Several area television stations have stopped releasing data on such political advertising, noting that federal law requires public disclosure only if the issue is of national importance.

Carl Kuhl, a spokesman for Emmer, noted that the campaign's $250,000 purchase pales in comparison to the millions Dayton and the Alliance spent during the primary promoting Dayton or attacking Emmer. He declined to speculate how much the Emmer campaign is prepared to spend in the last two months of the race.

Dayton spokeswoman Katharine Tinucci similarly declined to talk about the Dayton campaign's TV strategy. Horner's campaign said fundraising has picked up and the campaign would add to its media buy as more money comes in.

Dayton fleshes out specifics

But the campaigns aren't spending all their time on money-raising.

The three candidates have two more debates lined up this week, on economic policy and on issues related to seniors.

On Monday, Dayton kicked off the first in a series of candidate forums at the University of Minnesota's Humphrey Institute of Public Affairs with his plans for restructuring Minnesota's tax code. Emmer will follow suit on Wednesday, while Horner's forum will take place next Monday.

The former U.S. senator has pledged to raise taxes on the wealthiest Minnesotans, but said Monday that the top income tax rate would not be higher than Hawaii's 11 percent. After the event Dayton said that "10.8, 10.9 percent is probably where the top rate would be."

He said he would also create a third property tax bracket for homes valued at more than $1 million. Right now Minnesotans pay residential property taxes based on homes worth under $500,000 or over $500,000.

Dayton said he would also consider higher taxes on luxury goods such as high-end cars, boats and jewelry. "I'd look at luxury items, if you can isolate those," Dayton said.

As for specific tax rates and an analysis from the Department of Revenue, Dayton said after the event that he may withhold certain details until his opponents are more forthcoming about their plans.

"I've learned from their practice that putting my proposal out specifically while they keep their's totally obscure allows them to avoid the same kind of scrutiny that I have [endured]," Dayton said.

Curt Brown, Pat Doyle and Mike Kaszuba contributed to this report. Eric Roper • 612-673-1732