FILE - Independent candidate Ross Perot speaks as President George Bush, left, and Democratic candidate Bill Clinton listen during a debate in Richmond, Va., Oct. 15, 1992. An Associated Press analysis of Gallup data going back to 1980 shows that it's pretty common for third-party candidates to look like they have polling momentum in the months before an election, only to come up far short at the ballot box. (AP Photo/Ron Edmonds, File)