 Despite opinion polls leading up to the general election predicting a tight result , Labour decisively lost the 7 May general election to the Conservatives . Although gaining 22 seats , Labour lost all but one of its MPs in Scotland and ended up with a net loss of 48 seats , failing to win a number of key marginal seats that it had expected to win comfortably . After being returned as MP for Doncaster North , Miliband stated that it had been a " difficult and disappointing " night for Labour . Following David Cameron 's success in forming a majority government , Miliband resigned as Leader of the Labour Party on 8 May , with Harriet Harman becoming acting leader while a leadership election was initiated . 
