Primary night: What to watch

Three states are holding primaries or runoffs Tuesday. Here's a quick guide for the GOP and conservative races to watch.

South Carolina (7 p.m.) - If Nikki Haley doesn't defeat Rep. Gresham Barrett (R-S.C.) in the GOP primary for governor, it will be one of the great political upsets of all time. Most likely we'll have to settle for what, just a few months ago, would have seemed like an upset -- a clear Haley win. In the 1st district, Republicans will decide whether Tim Scott will become the first black GOP member of Congress since 2003, while in the 4th district conservatives expect to out Rep. Bob Inglis (R-S.C.)

Utah (10 p.m.) - The GOP primary for U.S. Senate pits businessman Tim Bridgewater against lawyer Mike Lee, with the bulk of tea party activists backing Lee and business interests backing Bridgewater. But pay attention, too, to Rep. Jim Matheson's (D-Utah) race in the 2nd district -- the conservative Democrat faces a surprise primary challenge from a progressive first-time candidate angry over his vote against health-care legislation.