Video: '1956 Senator Alben W. Barkley suffers heart attack after speaking at the Mock Democratic Convention'

(Monday, April 30, 1956, he collapsed at 5:15 p.m. EST, declared dead at 5:25 p.m. EST) — Alben W. Barkley, the 35th Vice President of the United States (1949-1953, under President Harry S. Truman), died today of a heart attack while addressing a student political convention at Washington and Lee University in Lexington, Virginia. He was 78.

Video: 'His Last Speech'

Barkley took an active role in the Truman administration, acting as its primary spokesman, especially after the Korean War required the majority of Truman’s attention.

Video: 'Alben Barkley’s Hidden Life: 10 Shocking Secrets That Will Blow Your Mind!'

When Truman announced that he would not seek re-election in 1952, Barkley began organizing a presidential campaign, but labor leaders refused to endorse his candidacy because of his age, and he withdrew from the race.