Theresa May is facing the prospect of a leadership battle with the 48 letters from MPs that would trigger a contest likely to be submitted this week, The Times has been told.

Tory challengers broke cover to set out their leadership pitches yesterday before the most difficult week of Mrs May’s troubled premiership.

Boris Johnson tried to put himself at the head of a jockeying pack by outlining plans for another negotiation with Brussels. Other former ministers refused to rule themselves out of a contest.

Some cabinet ministers were clinging to the hope that the prime minister would postpone tomorrow’s so-called meaningful vote on her Brexit deal as whips calculated that she was heading for a three-figure defeat.

This morning the cabinet was told by