So why is this changing now?
Like its impact on the rest of the UK, Brexit has upended the accepted order of British politics.
Over the past two centuries the prime minister’s authority has in most cases been guaranteed as the leader of the largest party in the House of Commons. Even during hung parliaments, when no single party commands a majority of seats, minority or coalition governments have managed to function effectively.
But the breakdown of old party loyalties following the EU referendum, exacerbated by disastrous decision to call the 2017 general election, which wiped out her working majority, has left the current PM in limbo – with more MPs questioning the “dictatorial” power of the executive during a time of national crisis.
During her time in office, May has effectively lost her parliamentary majority, suffered multiple Commons defeats – some of historic proportions – and seen a significant number of resignations from her government while in office.
“With the timetable now wrestled from her, May is in an incredibly weakened position and the numbers are such that she could even be considered the weakest prime minister in modern UK politics,” argues the Irish Independent.
What is more, according to the Attorney General Geoffrey Cox, any indicative motionpassed by MPs setting out a new route through the Brexit impasse would legally require the Government to follow Parliament’s instruction or risk breaching ministerial code.
“To put it another way, the PM would be obliged to endeavour to negotiate with the EU the revealed will of MPs, even if that revealed will involved a Brexit delay that requires the UK to participate in May’s European parliamentary elections, or is at odds with the Tories’ manifesto,” says ITV’s Robert Peston.
This would represent the ultimate transfer of power from executive to Parliament, setting a precedent that some claim could reshape British politics for years to come.
What did May say yesterday? The PM told Conservative MPs that she would step down if they passed her deal.
“I have heard very clearly the mood of the parliamentary party. I know there is a desire for a new approach – and new leadership – in the second phase of the Brexit negotiations – and I won’t stand in the way of that,” she said in the meeting.
“I am prepared to leave this job earlier than I intended in order to do what is right for our country and our party.”
But will her deal pass? It’s a tall order.
Northern Ireland’s Democratic Unionist Party are crucial to May if she wants her plan to succeed. Shortly after the Prime Minister’s bombshell announcement, the party confirmed they still can’t back her twice-defeated deal. The backstop, to which the party has been firmly opposed from the outset, still “poses an unacceptable threat to the integrity of the United Kingdom,” they said.
So where does that leave May? If she can’t get her deal through, it’s unclear whether she will step down. She will likely have to apply for a longer extension to Brexit, and might well still decide to leave and let someone else inherit the fallout. But that’s not what May outlined to MPs yesterday — so her future is still far from certain