Republican presidential candidates, former Pennsylvania Sen. Rick Santorum, former Massachusetts Gov. Mitt Romney, former House Speaker Newt Gingrich and Rep. Ron Paul, R-Texas, take the stage before the start of the Republican presidential candidate debate at the North Charleston Coliseum in Charleston, S.C., Thursday, Jan. 19, 2012. (AP Photo/Matt Rourke)
April 1, 2012 1:21:29 PM PDT
WASHINGTON - April 1, 2012 --
Mitt Romney's rivals are split on whether they would ever embrace the GOP presidential front-runner if he were the party's nominee.