The Conservatives and Liberal Democrats entered into a new coalition government, headed by David Cameron. Under the terms of the coalition agreement the government committed itself to hold a referendum in May 2011 on whether to change parliamentary elections from first-past-the-post to AV. Electoral reform was a major priority for the Liberal Democrats, who favour proportional representation but were able to negotiate only a referendum on AV with the Conservatives. The coalition partners campaigned on opposite sides, with the Liberal Democrats supporting AV and the Conservatives opposing it. The referendum resulted in the Conservative's favour and the first-past-the-post system was maintained.