BoehnerJohn BoehnerMarch is the biggest month for GOP in a decade House markup of ObamaCare repeal bill up in the air Conservatives to Congress: Get moving MORE will head to Boise on Aug. 26 for the fundraising lunch, which will also feature Idaho Gov. Butch Otter (R), according to Simpson's campaign.

The eight-term congressman is facing a potentially tough challenge from attorney Bryan Smith (R), who has the endorsement of the deep-pocketed, fiscally conservative Club for Growth. The organization's support has helped him get off to a quick fundraising start — he raised $150,000 in the first month of the campaign.

Simpson has long been attacked in his state for not being conservative enough and has faced primary challenges in the past. But this is the first time that a challenger has had serious money behind him, and the Speaker is looking to shore up a key ally. 

Simpson has $335,000 in the bank for the campaign.