The Campaign for Primary Accountability, a super PAC that's raised $2.5 million and has been active in about a dozen races across the country, maintains that long serving incumbents should be ousted because their campaigns are accountable to lobbyists, not district voters. Yet in one district, the challenger it's backing in Tuesday's Indiana primary is a former House member who went on to work as a registered lobbyist.

Recently, the super PAC helped oust Rep. Tim Holden, D-Pa., by calling him a friend to K Street. Part of the problem with incumbents, according the group's website, is that "lobbyists shower them with campaign funds." The super PAC attacks incumbents for raising money "mostly from lobbyists and special interests" and "never speak[ing] of the earmarks, pay raises, junkets and generalized corruption" in Congress. But in Indiana's 5th congressional district, the group is spending about $130,000 in support of ex-congressman and registered lobbyist David M. McIntosh over seven Republican primary challengers who are neither registered lobbyists nor former incumbents. This is the first open race that the super PAC is active in.

McIntosh is running for the seat created when Rep. Dan Burton, R-Ind., retired after the Campaign for Primary Accountability threatened to spend against him in the primary. After losing his bid for governor, McIntosh went to work for lobbying heavyweight Mayer Brown, representing clients that included the U.S. Chamber of Commerce, the Royal Bank of Canada and Arkema, a chemical manufacturer. And while working as a lobbyist, McIntosh donated thousands of dollars to longtime Washington incumbents.

One of the recipients of his K-Street largesse was Rep. Spencer Bachus, R-Ala., to whom McIntosh donated a total of $1,000. The Campaign for Primary Accountability unsuccessfully tried to take Bachus down in a February primary for his "Bacchanalia of sleaze." Two other recipients of McIntosh's dough are long-term senators Orrin Hatch, R-Utah and Dick Lugar, R-Ind., both of whom are up for reelection this year and facing an anti-incumbent electorate.

Not to mention that McIntosh once donated $500 to Burton himself for his 2008 campaign. An official for the McIntosh campaign did not return multiple phone calls Monday.

McIntosh has attacked his main fundraising challenger, former U.S. attorney Susan Brooks, as a supporter of the Troubled Assets Relief Program, known as the bank bailout. However, the Royal Bank of Canada, which hired McIntosh in 2011, has a U.S. subsidiary that received bailout funds. Another client, the Chamber of Commerce, has given Burton its "Spirit of Enterprise" award year after year.

McIntosh is still a partner at Mayer Brown but went on leave as of March 1. He has not done any client work this year, the firm's spokesman Bob Harris said.

Campaign for Primary Accountability spokesman Curtis Ellis said he was "not familiar" with McIntosh's lobbyist background and would not comment on it. But he added that the group has no problem endorsing past or current members of Congress or, for that matter, lobbyists.

He said that the Tea-Party-linked group's mission went beyond taking down incumbents, which has been the group's main message. The group decided to stay in the Indiana race "to encourage strong candidates and serious citizens everywhere—Republicans and Democrats—to challenge entrenched incumbents in all districts," Ellis said.