 Following the formation of the Conservative – Liberal Democrat Coalition Government on 11 May 2010 , Gordon Brown resigned as Prime Minister and Leader of the Labour Party with immediate effect . In accordance with the Labour constitution , Deputy Leader Harriet Harman took over as Acting Leader and became Leader of the Opposition . On 14 May , Miliband announced that he would stand as a candidate in the forthcoming election for the leadership of the Labour Party . He launched his campaign during a speech given at a Fabian Society conference at the School of Oriental and African Studies and was nominated by 62 fellow Labour MPs . The other candidates were left @-@ wing backbencher Diane Abbott , Shadow Education Secretary Ed Balls , Shadow Health Secretary Andy Burnham and Miliband 's elder brother , Shadow Foreign Secretary David Miliband . 
