In a referendum held on 23 June 2016 on whether the UK should leave the European Union (EU). As of the day before the referendum, 185 Conservative MPs declared they would vote to remain and 138 declared they would vote to leave. Phillips supported a withdrawal from the EU. The Labour Party and the Liberal Democrats officially supported the continuation of EU membership. UKIP supported the UK's withdrawal from the EU, which was the party's main policy. The UK voted to leave the EU, with approximately 52% of votes cast in favour of withdrawal from the EU. The UK did not leave immediately; the referendum result led to a period of negotiations between the UK and the EU. The Conservative Party was officially neutral in the referendum, although Cameron campaigned to remain. Immediately after the referendum result was announced, Cameron resigned as prime minister. He was replaced in July 2016 as Conservative leader and as Prime Minister by Theresa May.