A jubilant Rick Santorum is leveraging victories in Colorado, Minnesota and Missouri to increase pressure on Mitt Romney, labeling him "a well-oiled weather vane" who often shifts his positions.

Republicans in Colorado and Minnesota are holding their presidential caucuses Tuesday, and Mitt Romney is hoping he hasn't ignored Rick Santorum's attacks for too long.

New national polling of the 2012 Presidential Race conducted by Rasmussen Reports shows that Rick Santorum in a virtual tie with President Barack Obama.

Republican presidential candidate Rick Santorum says Newt Gingrich shouldn't be urging him to drop out of the primaries.

Pennsylvania's state Republican Party committee members are gathering in Hershey as a clash brews over whether or who to endorse in the crowded field of candidates vying for the party's U.S. Senate nomination.