The 1961 Labour Party leadership election was held when, for the second year in succession, the incumbent leader was challenged for re-election. Normally the annual re-election of the leader had been a formality.
The challenge followed factional in-fighting over issues like nuclear disarmament. The leader favoured the retention of nuclear weapons by the UK, whereas the left wing of the party supported the Campaign for Nuclear Disarmament.
The left-wing candidate the previous year had been Harold Wilson. In 1961 the candidate was a less well-known political figure, Tony Greenwood (1911– 1982), then MP for the Lancashire constituency of Rossendale. He had been an MP since 1946 and was the son of Arthur Greenwood (1880–1954), who had been a Labour leadership candidate in 1935.