After MPs yesterday threw a spanner in the works of a potential No Deal Brexit, the Prime Minister faces another challenge today.
It looks as if the Speaker has accepted an amendment from the senior Tory backbencher Dominic Grieve which would force Theresa May to come to Parliament within three days - if her Brexit deal is defeated next week. She currently has about a month to come forward with a Plan B.
It's an unprecedented situation.
The Brexit debate is set to continue after Prime Minister's Questions.
Normally, backbenchers wouldn't be able to amend a Business Motion in these circumstances.
But one of the amendment's signatories told me that with another month effectively wasted after Mrs May pulled the 'meaningful vote' before Christmas, and with no sign that anything new was on offer, it was vital that MPs step in to look at alternatives to her deal.