Jimmy Hoffa Agreement. He played a major role in the growth and development of the union, which eventually became the largest (by membership) in the United States with over 2.3 million members at its peak, during his terms as its leader. Hoffa became involved with organized crime from the early years of his Teamsters work, and this connection continued until his disappearance in 1975. He was convicted of jury tampering, attempted bribery and fraud in 1964, in two separate trials. He was imprisoned in 1967 and sentenced to 13 years. In mid-1971, he resigned as president of the union as part of
Jimmy Hoffa bid in 1972; in prior elections, the union had supported Democratic nominees but had also endorsed Nixon in 1960. Suspicion was soon raised of a deal for Hoffa's release connected with the IBT's support of Nixon. It was alleged that a large sum of money, estimated to be as high as $1 million, was paid secretly to Nixon. Evidence was also alleged of a secret bribe paid in 1960. While glad to regain his freedom, Hoffa was very disappointed with the condition imposed on his release by President Nixon, which prevented Hoffa from engaging in union activities until March 1980.