In a cabinet reshuffle on 13 May 2008, following the election of Brian Cowen as Taoiseach, Martin became Minister for Foreign Affairs. One of the first issues that he had to deal with was the referendum on the Treaty of Lisbon. Martin led the government campaign. Despite the overwhelming majority of government and opposition parties supporting a Yes vote, the electorate rejected the government's recommendation. Martin and Cowen failed to convince the Irish public to support the ratification of the Treaty of Lisbon, and this protest expressed in the referendum on 12 June 2008 plunged the government into a major political crisis.