Tom Smith, the eventual nominee, faced David A. Christian, Sam Rohrer, Marc Scaringi, and Steve Welch.

Incumbent Bob Casey, Jr., defeated Joseph Vodvarka by a wide margin.

Casey led most pre-election polls and eventually defeated his opponents to win re-election to a second term in the U.S. Senate.

This is also the only time since 1956 that Democrats have won a Pennsylvania U.S. Senate race in a presidential year.

In January 2012, the Pennsylvania Republican Party officially endorsed Steve Welch for U.S.

The only Democrat he donated to was Congressman Jason Altmire, a moderate Blue Dog.

Rohrer was endorsed by various tea party organizations, as well as U.S. Congresswoman Michele Bachmann and 2012 Republican presidential candidate Herman Cain.

Casey also won the surrounding collar counties of Bucks, Chester, Delaware, and Montgomery, which are seen as vital in statewide elections in Pennsylvania.

Smith did well in rural counties, but it wasn't enough to overcome the lead Casey had built in the huge population centers.