A political watchdog group filed a complaint against three conservative organizations Thursday, accusing them of violating Minnesota's campaign finance rules to avoid disclosing donors.

Common Cause Minnesota alleges that Minnesota's Future, a group that funds ads attacking DFL governor candidate Mark Dayton, improperly funneled donations from the Republican Governors Association through a "shell corporation."

The RGA donated about $400,000 this summer to "Minnesota Future, LLC," which then gave the money to Minnesota's Future, a political action committee. The RGA donation was disclosed on campaign finance filings, but Common Cause Executive Director Mike Dean argues that Minnesota law requires disclosure of the RGA's donors.

Common Cause filed a complaint with the Campaign Finance and Public Disclosure Board against all three entities. "I believe there was clear intent to avoid the disclosure law here," Dean told reporters at the Capitol.

The Democratic Governors Association made similar donations to a liberal group called WIN Minnesota – which also helps fund attack ads – but Dean said the WIN's tax status means they are not required to disclose the DGA's donors.

"The issue is one organization followed the law, and the other organization did not," Dean said.

Chris Tiedeman, the head of Minnesota's Future, said they are in compliance with the law.

"It's clear that Common Cause is simply a DFL front group trying to shut down our legitimate right to participate in this political process," Tiedeman said.