The newest nerve center of Democratic fundraising power in Minnesota resides in a dingy St. Paul office filled with mismatched furniture and a whiff of an animal hospital that shares the building.

Inside, a web of independent groups is busy spending enough money in this election to make Republicans quake. The group's public face is known as Alliance for a Better Minnesota, backed by its fundraising arms, WIN Minnesota and the 2012 Fund. Together, they have hauled in $3 million this year and $8 million over the past four, all for a single goal: winning back a Democratic Legislature on Tuesday.

The outside groups work with the DFL where they can, trading staff, research and polls, but say they are careful not to cross legal barriers.

"It's not super sexy, but it's a huge change on our side," said Carrie Lucking, executive director of the Alliance for a Better Minnesota.

House Speaker Kurt Zellers, a GOP leader whose state party is trying to keep control of the Legislature after a year beset by controversy, sees that mission differently.

"It is very concerning that one group would just be able to buy the Legislature for the governor," said Zellers, R-Maple Grove. "I also think that's why it won't work."

Lucking points out that Minnesota Republicans in the past have benefited from big donors and organizational cross-ties and even now are getting help from Minnesota's Future, the Freedom Club and wealthy donors such as business heavyweight Bob Cummins.

"If Mr. Zellers is concerned about buying the Legislature, he should talk to his corporate donors," Lucking said.

By working off the same playbook, the coalition and the party have developed a two-fisted punch that is proving powerful.

Large donors, like unions, are able to give to both groups, doubling their ability to spread a unified message. Chief among donors is Alida Messinger, an heir to the Rockefeller fortune who has pumped more than $850,000 into the coalition this year, making her the single largest individual contributor. Combined with her donations to the DFL Party and the campaigns to defeat the marriage and photo ID amendment, Messinger has moved $1.5 million into Minnesota politics in 2012. She is Gov. Mark Dayton's ex-wife.

Messinger's close connection to the governor is far from the only intertwining of political and personal interests that run through the Alliance's work.

Ken Martin led both the 2012 Fund and WIN before he became DFL Party chairman last year. Jeff Blodgett, formerly of Wellstone Action, took over leadership of the two groups briefly before going on to head President Obama's Minnesota campaign. Adam Duininck, a former union staffer and Dayton appointee to the Metropolitan Council, took over the 2012 Fund and WIN from Blodgett. He is married to Jaime Tincher, who works in Dayton's gubernatorial office.

Alliance's Lucking is romantically partnered with Dayton's communications chief, Bob Hume. Lucking, who worked for Democrats in the Legislature before she became Alliance's executive director, said the two consulted an attorney to figure out exactly what they could and could not talk about at home, to keep from violating rules that require them not to coordinate.

A 'new revolving door'

University of Minnesota professor Larry Jacobs said such close connections are no longer unusual in politics.

"The new revolving door is between these independent expenditure groups and these campaigns and government offices," he said.

Denise Cardinal, who led the Alliance in 2010, said that working in Democratic politics in a lesser-populated state like Minnesota means bumping into the same people in different capacities.

She now heads Project Lakes and Plains, a taxable nonprofit that does polling and research for clients that include Alliance, Senate and House Democratic campaigns and the DFL Party. Those four groups have paid Lakes and Plains more than $550,000 this year.

The coalition has developed other tentacles that reach out through the state's politics. Alliance has a nonprofit just for federal elections. WIN Minnesota has a nonprofit arm that funds groups working on issues from boosting minority voting to improving gay rights. Those groups share many of the same staff and board members with Alliance, WIN Minnesota and the 2012 Fund.

The result has been an unusually seamless Democratic campaign for the Legislature.

The Alliance has funded statewide television ads to attack Republican lawmakers and followed up with more than 5,000 cable spots and hundreds of mailings that target specific lawmakers. It spent more than $84,000 to hammer just one senator, Brooklyn Park Republican Benjamin Kruse.

But the Alliance is not playing alone. The Republican-friendly Freedom Club has spent $117,0000 to attack Kruse's Democratic opponent, John Hoffman.

Kruse says the flood of money makes him "uncomfortable" and may have an unintended consequence.

"The constituency turns off," he said.

Rachel E. Stassen-Berger Twitter: @rachelsb