Keir Starmer should step aside in favour of a caretaker prime minister who would run the country until a leadership contest is held in the summer, Labour MPs have argued. Despairing Government backbenchers argue that unless the Prime Minister quits over the Peter Mandelson crisis, the party is heading for disaster at the Gorton and Denton by-election later this month – followed by annihilation in May’s local elections. They hope the Cabinet will this week persuade Sir Keir to quit and allow a ‘non-contentious’ candidate such as Defence Secretary John Healey or Northern Ireland Secretary Hilary Benn to be a...