From left, Sen. Jeff Flake, R-Ariz., Sen. Chuck Schumer, D-NY, Sen. John McCain, R-Ariz., and Sen. Michael Bennett, D-Colo, arrive at a news conference after their tour of the Mexico border with the United States on Wednesday in Nogales, Ariz. The senators are part of the "Gang of Eight," a larger group of legislators collaborating on changes to immigration. Ross D. Franklin/AP hide caption

itoggle caption Ross D. Franklin/AP

Can our nation afford political waffling on issues of scientific consensus? Stan Honda/AFP/Getty Images hide caption

itoggle caption Stan Honda/AFP/Getty Images

Florida U.S. Senate candidates Marco Rubio (from left), Charlie Crist and Kendrick Meek share a laugh before their debate Wednesday. Joe Burbank, Pool/AP hide caption

itoggle caption Joe Burbank, Pool/AP