As Republican voters take their head of steam toward the November elections, California's congressional Democrats nonetheless feel secure that they will survive an otherwise brutal experience. All except one: Jerry McNerney, the congressman from eastern Alameda County. McNerney first came to power in 2006, riding a wave of anti-Republican sentiment and defeating rancher Richard Pombo, who had held the seat for seven terms. (See this excellent Robert Gammon piece for a taste of Pombo's cowboy libertarian ways.) But as the Chronicle's Drew Joseph notes, the district is pretty evenly split between suburban liberals and conservative rural residents, and Republican rising star David Harmer is mounting a serious challenge. Fun fact: California law actually allows carpetbagging; Harmer doesn't live in the district, but is legally allowed to run for the seat anyway. Who knew?