** FILE ** Sen. Pat Roberts, Kansas Republican, sings a song at "A Century of Service" honoring former U.S. Senate Majority Leaders  Bob Dole and Howard Baker at Mellon Auditorium, Wednesday, March 21, 2012, in Washington. (AP Photo/Carolyn Kaster)

Photo by: Carolyn Kaster

** FILE ** Sen. Pat Roberts, Kansas Republican, sings a song at "A Century of Service" honoring former U.S. Senate Majority Leaders Bob Dole and Howard Baker at Mellon Auditorium, Wednesday, March 21, 2012, in Washington. (AP Photo/Carolyn Kaster)