Nevada Gov. Brian Sandoval, left, greets workers at a registration table during early voting at the Carson City Republican Caucus, Saturday, Feb. 4, 2012, in Carson City, Nev. (AP Photo/Ted S. Warren)

Early voters line up just before 7:00 a.m., to vote in the Carson City County Republican Caucus, Saturday, Feb. 4, 2012, in Carson City, Nev. The county offered an early "vote and go" option for people who had work or other obligations later in the day when the regular caucus meeting was scheduled. (AP Photo/Ted S. Warren)

Texas Governor Rick Perry, from left, Mitt Romney and Herman Cain attend the Republican presidential debate at DAR Constitution Hall in Washington, D.C., Tuesday, November 22, 2011. (Olivier Douliery/Abaca Press/MCT)

Newt Gingrich answers a question during the Republican presidential debate at DAR Constitution Hall in Washington, D.C., Tuesday, November 22, 2011. (Olivier Douliery/Abaca Press/MCT)

Texas Rep. Ron Paul attends the Republican presidential debate at DAR Constitution Hall in Washington, D.C., Tuesday, November 22, 2011. (Olivier Douliery/Abaca Press/MCT)

Rick Santorum attends the Republican presidential debate at DAR Constitution Hall in Washington, D.C., Tuesday, November 22, 2011. (Olivier Douliery/Abaca Press/MCT)