Rep. William Lacy Clay Jr. (D-MO) defeated fellow Rep. Russ Carnahan (D-MO) on Tuesday in the latest of a series of intra-party turf wars spurred by redistricting.

Carnahan, who sought a fifth term, was drawn out of his current district due to Missouri's slow population growth over the last decade. He ran against Clay, who has served since 2001, over another open but Republican-leaning district. But the incumbent-on-incumbent race - with tensions already running high - became especially thorny as the issue of race emerged in the campaign. 

Carnahan, who is white, faced Clay, who is African-American, in a St. Louis-area district with a historically large black population. The newly drawn district includes nearly 70 percent of the same territory Clay currently represents. But parts of Carnahan's old district amounted to about a third of the new area represented by the First District.