Sen. Christopher Dodd, D-Conn., left, with then-Senate Minority Leader Tom Daschle at a 1995 news conference on Capitol Hill. Harry Reid took over as leader in 2005 after Daschle unexpectedly lost his re-election. At the time, Reid was unknown to most Americans, but he beat back a challenge Dodd. John Duricka/AP hide caption

itoggle caption John Duricka/AP

Sen. Charles Schumer of New York stands a podium March 3 as Senate Minority Leader Harry Reid of Nevada looks on. Reid is backing Schumer to be his replacement as Democratic leader. J. Scott Applewhite/AP hide caption

itoggle caption J. Scott Applewhite/AP

Senate Minority Leader Harry Reid of Nevada and Sen. Charles Schumer, D-N.Y. Reid said today that he won't seek re-election in 2016, adding he wants Schumer to succed him as the Democratic leader in the Senate. Molly Riley/AP hide caption

itoggle caption Molly Riley/AP