BOISE, Idaho (AP) — Making the word "liberal" stick to eight-term Congressman Mike Simpson in deeply conservative Idaho is no easy task.

So when challenger Bryan Smith applies it, he's careful to qualify it by saying Simpson is "too liberal for Idaho." How that plays out in the GOP primary for Idaho's 2nd Congressional District will be decided Tuesday. Simpson cites endorsements by the National Rifle Association and fellow Idaho Sen. Jim Risch, one of the U.S. Senate's most conservative members.

Smith, an attorney, cites his endorsements by the conservative groups and tea party favorites Club for Growth, American Conservative Union and FreedomWorks. The congressional seat that represents the heavily Republican district is considered a safe bet in November for the candidate who wins the primary.