was the result of the New Zealand Labour Party’s victory in the 1984 election. On 12 June 1984, Richard Prebble introduced the Nuclear Free New Zealand Bill, which called for the exclusion of nuclear powered ships from New Zealand. New Zealand National Party MP Marilyn Waring threatened to cross the floor and vote for Prebble's anti-nuclear bill. This challenged Prime Minister Robert Muldoon's leadership, as the National Government had a majority of only one person in Parliament. Muldoon announced on 14 June 1984 that he would call a snap election. The question of nuclear ship visits became central to the 1984 election.