RENTON, Wash. -- The evening rush hour has begun in earnest, and "Gas Pump Man," a comic book-like character with a costume made of foam, is on the scene, waving his pump and urging harried drivers to honk if they want lower gas prices. By his side are volunteers for Darcy Burner, the Democratic challenger to Republican U.S. Rep. Dave Reichert in this suburban Seattle district, holding a homemade banner urging motorists to "Tell Congressman Reichert to take back the $14 billion in subsidies he gave to big oil." In the battle for Congress, the high price of gasoline has...