Photo: Udall, Gardner debate (AP Photo)

Incumbent U.S. Sen. Mark Udall, D-Colo., left, and his opponent U.S. Rep. Cory Gardner, R-Colo., face off during a televised debate at 9News in Denver, Wednesday Oct. 15, 2014. Colorado's U.S. Senate candidates met for their final televised debate before election day on Nov. 4.