The American Action Network, a conservative advocacy group co-founded by former Minnesota U.S. Sen. Norm Coleman, has reserved $860,000 in television advertising time in the Twin Cities market for the fall election season.

The Minnesota reservation is part of a $6 million campaign in key media markets to promote House Republicans facing tough re-election battles this November.

"This initial investment for the fall will enable the Network to directly communicate with local households about the key congressional candidates and issues in their area," spokeswoman Brook Hougesen said.

The move comes as Democrats in Congress ramp up their criticism of non-profit groups, such as the American Action Network, that aren't required to reveal their donors.

Senate Republicans on Monday blocked consideration of a Democratic bill, the DISCLOSE Act, that would require non-profits to reveal donors who contribute at least $10,000. Minnesota Sens. Al Franken and Amy Klobuchar are among backers of the DISCLOSE Act.

Since the 2010 U.S. Supreme Court Citizens United ruling paved the way for corporations, unions and other special interests to spend money directly advocating for individual candidates in elections, Senate Democrats have tried to pass legislation requiring the non-profits to disclose their backers.

In the 2010 campaign, the American Action Network spent more than $25 million on ads, with most of the money coming from secret donors. During that election, the group ran ads in Minnesota supporting U.S. Rep. Chip Cravaack's successful congressional campaign and U.S. Tim Walz's opponent.

The American Action Network's latest foray into the Minneapolis market mirrors the efforts of a super PAC and union plan to run ads targeting Cravaack and U.S. Rep. John Kline, both of Minnesota, and Wisconsin U.S. Rep. Reid Ribble.

As part of Democratic efforts to win back control of the U.S. House, the Democrat-led House Majority political action committee and Service Employees International Union plan to spend $890,000 on television ad time in the Twin Cities market in the weeks leading up to the election.