After Hart withdrew from the race, no clear frontrunner emerged before the primaries and caucuses began. The Iowa caucus was won by Dick Gephardt, who had been sagging heavily in the polls until, three weeks before the vote, he began campaigning as a populist and his numbers surged. Illinois Senator Paul M. Simon finished a surprising second, and Massachusetts Governor Michael Dukakis finished third. In the New Hampshire primary, Dukakis came in first, Gephardt fell to second, and Simon came in third. In an effort to weaken Gephardt's candidacy, both Dukakis and Gore ran negative television ads against Gephardt. The ads convinced the United Auto Workers, which had endorsed Gephardt, to withdraw their endorsement; this crippled Gephardt, as he relied heavily on the support of labor unions.