Primary Narrows McCaskill Challengers

It's a big day for Missouri's Claire McCaskill. The embattled senator will finally learn, after the votes are tallied in today's congressional primary, who she'll be running against in November. There are currently three Republicans vying to replace the vulnerable Democrat, but the McCaskill camp is believed to hope Rep. Todd Akin, considered less aggressive than the others, will be her opponent. Michigan, Washington, and Kansas are all holding their primaries today as well.