A centrist group run by a former Republican congressman on Tuesday blasted the fiscally conservative Club for Growth as a "cancer" on the GOP and promises to match the organization "dollar for dollar" in the primaries it targets.
"The Club for Growth is a cancer on the Republican Party that prides itself on supporting rigid, divisive and obstructionist candidates," said LaTourette, who like Simpson is a close ally of Speaker John Boehner (R-Ohio).
"They are certainly entitled to support any candidate they want for any reason they want, but it would be nice if they told the voters the truth about their organization," he said. "And if they won't tell voters the truth, we will."
The group isn't the first to oppose the Club in primaries. The Young Guns, a group run by former staffers for House Majority Leader Eric Cantor (R-Va.), butted heads with the Club in 2012, with mixed results.
The center-right American Action Network challenged the Club in a few races as well. But it's the first time that a group has publicly stated one of its top goals is to fight back against the group.
Main Street Advocacy Fund calls the Club for Growth ideological "chameleons," highlighting a dozen votes where the group's president, former Rep. Chris Chocola (R-Ind.), voted the same way as Simpson — and against the wishes of the Club.
The Club fired back in a statement criticizing Simpson.
"It's a joke for Mike Simpson and his allies to cry foul on outside groups supporting his conservative challenger — 64 percent of Mike Simpson’s campaign contributions have come from Washington PACs, not the people of Idaho," Club for Growth spokesman Barney Keller said.
"Mike Simpson’s voting record is what is at issue, and he has repeatedly joined with a small minority of his own party and Democrats to grow government."
Simpson has a 58 percent lifetime conservative rating on the Club's scorecard. The group has endorsed Idaho attorney Bryan Smith in the Republican primary in Simpson's district.
An earlier version of this post incorrectly stated the name of the Main Street Advocacy Fund.