SANDPOINT, Idaho -- Bill Sali is defying the political odds by making Idaho's first-district congressional race competitive. That isn't good for Mr. Sali: He is the incumbent.

A 54-year-old Republican from Kuna, 18 miles from Boise, Mr. Sali represents one of the most heavily Republican electorates in the U.S. The district hasn't elected a Democrat to the House since 1992; in the 2004 presidential race, 69% of its votes went to George W. Bush.

But...