Former Massachusetts Gov. Mitt Romney, a Republican presidential candidate, speaks to supporters outside City Hall in Nashua, N.H., on Sunday. Sen. Kelly Ayotte (left) of New Hampshire listens. Mrs. Ayotte endorsed Mr. Romney.  (Associated Press)

Former Massachusetts Gov. Mitt Romney, a Republican presidential candidate, speaks to supporters outside City Hall in Nashua, N.H., on Sunday. Sen. Kelly Ayotte (left) of New Hampshire listens. Mrs. Ayotte endorsed Mr. Romney. (Associated Press)