Former House Speaker Newt Gingrich listens as he is introduced during a campaign stop in Manchester, N.H., on Wednesday. Mr. Gingrich traded jabs with Mr. Romney on the stump. He tied Mr. Romney to "falsehoods" in campaign ads. Rep. Ron Paul of Texas,(right), a GOP presidential hopeful, speaks during a campaign stop in Fort Madison, Iowa, on Wednesday. The lawmaker has been linked to anti-Gingrich campaign ads in Iowa.