A super PAC that defends Republican incumbents went up on air Thursday with an ad that both touts Idaho Republican Rep. Mike Simpson’s conservative credentials and attacks the outside groups seeking to oust him in an upcoming primary.  

The ad, released by Defending Main Street, seeks to discredit the Club for Growth — the main group attacking Simpson in the May 20 primary . It ties Club for Growth President Chris Chocola to House Minority Leader Nancy Pelosi, D-Calif., a villain to the Republican Party, and questions the club’s priorities.  

“His group spends more money trying to defeat Republicans than defeating Democrats,” the narrator accuses, before going on to highlight Simpson’s votes against the Affordable Care Act and his endorsement from the National Rifle Association.  

https://youtu.be/l9LioYqy35A  

The ad is backed by a six-figure buy and will air for three weeks, according to a source familiar with the buy. Defending Main Street is a super PAC run by former Rep. Steve C. LaTourette, R-Ohio., who laments the rise of conservative outside groups like the club.  

It’s just the latest in a line of ads that are flooding Idaho’s 2nd District in the run-up to the primary.  

Simpson faces attorney Bryan Smith in the primary. Smith has the endorsement of tea party groups such as the club and the Senate Conservatives Fund .  

Simpson, on the other hand, is backed by 2012 GOP presidential nominee Mitt Romney and House Budget Chairman Paul D. Ryan, R-Wis.  

The primary victor will be the heavy favorite in November. Romney carried the seat by a 31-point margin in 2012.  

Idaho’s 2nd District is rated a Safe Republican contest by Rothenberg Political Report/Roll Call.