Former House Speaker Newt Gingrich greets former candidate Herman Cain during a campaign stop in Tampa, Fla., on Monday. Mr. Cain has endorsed Mr. Gingrich in the presidential race. (Associated Press)

Former House Speaker Newt Gingrich greets former candidate Herman Cain during a campaign stop in Tampa, Fla., on Monday. Mr. Cain has endorsed Mr. Gingrich in the presidential race. (Associated Press)