Clements began his campaign for re-election in 1956 by defeating Joe Bates, the candidate favored by Chandler, in the Democratic senatorial primary. On April 30, 1956, Kentucky senator Alben Barkley died suddenly of a heart attack. With the Democratic primary already over, the Democratic State Central Committee was charged with selecting a candidate to run for Barkley's seat. They chose Wetherby, Clements' former lieutenant governor. Journalist John Ed Pearce later recorded that Clements had favored Chandler's choice, Joseph Leary, as a candidate rather than Wetherby. Clements didn't think Leary had a very good chance of winning, but he felt Leary's selection would keep Chandler from throwing his support to the Republican candidates.