Sheldon Adelson. Mike Clarke/AFP/Getty Images hide caption
Former House Speaker Newt Gingrich, who wants to the the 2012 Republican presidential nominee, during a campaign event in Camp Hill, Pa., on Saturday (March 24, 2012). Jessica Kourkounis/Getty Images hide caption
Former House Speaker Newt Gingrich. Win McNamee/Getty Images hide caption
After his losses in Alabama and Mississippi on Tuesday, Newt Gingrich will face increasing pressure to drop out of the GOP race. Here he waves to supporters after speaking at a rally in Hoover, Ala., on Tuesday. Marvin Gentry /Reuters /Landov hide caption
Former Speaker of the House Newt Gingrich speaks at a rally with his wife, Callista, on Thursday in Jackson, Miss. Marianne Todd/Getty Images hide caption
Republican presidential candidate and former Speaker of the House Newt Gingrich on Tuesday in Duluth, Ga. Alex Wong/Getty Images hide caption
Newt Gingrich shakes hands during a campaign rally Tuesday in Rome, Ga. Evan Vucci/AP hide caption
Republican candidate Newt Gingrich is counting on his promise of $2.50-per-gallon gas to return him to front-runner status. Evan Vucci/AP hide caption
Former House Speaker Newt Gingrich waves during a campaign stop Friday in Peachtree City, Ga. Doing well in the state's primary is important for Gingrich because he represented a congressional district there for 20 years. Evan Vucci/AP hide caption
Former House Speaker Newt Gingrich addresses the Conservative Political Action Conference in Washington, D.C., on Friday. Win McNamee/Getty Images hide caption
On Thursday night in Jacksonville, Fla., Mitt Romney (right) went after Newt Gingrich from the start on topics such as immigration and colonizing the moon. Matt Rourke/AP hide caption