Ryan endorses Simpson in Idaho primary
© Greg Nash

Rep. Paul RyanPaul RyanAs Congress adjusts to Trump, Iran put under the pressure it deserves The Hill's 12:30 Report Biz groups push for regulatory reform in new Congress MORE (R-Wis.) on Tuesday endorsed Rep. Mike Simpson (R-Idaho), giving him a boost against his Tea Party challenger.

"Mike Simpson has been in the trenches fighting to reform runaway spending and has been a critical voice in passing our plan to balance the budget and pay down our debt," Ryan said in a statement released by Simpson's campaign.

Ryan is a favorite of conservatives, and Simpson, a close friend of Speaker John Boehner (R-Ohio), is looking to shore up his credentials on the right as he faces Tea Party candidate and attorney Bryan Smith (R).

Smith has the backing of the conservative Club for Growth and has raised more money than most other conservative primary challengers this election cycle. Simpson has been endorsed by the Chamber of Commerce, which has been airing ads on his behalf.