Since edging out Harmer by 1.1 percent in November, McNerney's made the Democratic Congressional Campaign Committee's list of vulnerable incumbents, and was targeted this month by a National Republican Congressional Committee TV ad.

Sensing an opportunity, 24-year-old Republican Ricky Gill has thrown his hat in the ring to challenge McNerney, according to The Sacramento Bee. He's expected to be joined by others, but other Republicans are waiting to see how the district, where the GOP currently has a narrow registration advantage, looks after redistricting.

Another name being mentioned is Elizabeth Emken, a former executive at Autism Speaks, an advocacy group. "Elizabeth is thinking about the race," said Clark, who has yet to sign onto an 11th district campaign. "She's preparing for the race. We all expect she'll get in the race" unless the district is radically redrawn.

Sources say it's also possible, but unlikely, Harmer runs again.