Former Georgia state Sen. Regina Thomas has announced she will seek a rematch with Rep. John Barrow (D-Ga.) in the primary next year.

Thomas, you'll recall, scared Barrow enough for the congressman to solicit some help from President Obama. Obama delivered with a radio ad, and Barrow won easily, 76-24.

It's hard to see how Thomas gains much more traction this time, unless Barrow votes with Republicans on some key issues. But he did that before, and it didn't seem to hurt his primary prospects.

At same time, it's important to note that the district remains 44 percent black, which could help an African-American former state legislator like Thomas. But that alone hasn't been enough to sink Rep. Steve Cohen (D-Tenn.), even in a majority-black district.

Barrow, Cohen and Rep. Allen Boyd (D-Fla.) all face primary challenges from black candidates in primaries with significant black electorates. All appear strong favorites at this point.