Dr. Ami Bera of California has raised more than a half-million dollars for a rematch against Rep. Dan Lungren (R-Calif.), the latest sign that the incumbent will have a tough race on his hands next fall. Bera has about $450,000 in the bank for the election.

Bera, one of the Democrats' most highly touted recruits in 2010, lost to Lungren 43 percent to 50 percent in the Republican-friendly year. The current district is slightly Republican-leaning, although it went narrowly for President Obama in the 2008 presidential election.

Bera, a physician, was the only Democratic challenger to out-raise a sitting House Republican in the cycle, although conservative outside groups like American Crossroads spent money to keep Lungren in the race.

This time, the two could be fighting on more Democratic territory. California's newly created Bipartisan Redistricting Commission has put out draft maps that would make Lungren's Sacramento-based district more liberal by lopping off some of the more conservative, rural parts of the district and centering it more on the state capitol.

The committee has yet to finish its work, and the changes in the district aren't huge, but in California in a presidential year Bera might have the edge, and his big fundraising numbers will only add to his chances.