Prime Minister Theresa May has suffered another significant defeat to her Brexit plan, after MPs voted on Friday to reject her withdrawal agreement.

On the day the U.K. had originally been due to leave the EU, the House of Commons shot down the prime minister’s eleventh hour attempt to lock in a short extension of Article 50 until May 22 which she said would “guarantee Brexit”.

The defeat means the U.K. is on course to leave with no deal on April 12 — unless the government comes up with an alternative plan.

Speaking in the Commons, May said this alternative would likely now be a much longer delay to Brexit which could “destroy” the attempt to leave the EU.

“Today should have been the day the U.K. left the EU — that we are not leaving today is a matter of deep personal regret to me,” she said.

In a last-ditch attempt to persuade Tory rebels to vote with her, May had also promised to resign as prime minister if the Commons backed her.

The offer to let a new party leader and PM to take charge of the next phase of the talks with the EU – the future trade relationship – persuaded some to fall in line.

Leading Brexiteers including Boris Johnson and Dominc Raab decided to vote with the government.

But it was not enough in the face of continued opposition from the DUP, a hardcore of pro-Brexit Tories and the Labour Party.

Labour leader Jeremy Corbyn said today’s vote was an “affront to democracy”. He said: “The government has run down the clock in an attempt to blackmail MPs at every turn.”

In an attempt to win over critics, May asked parliament to only vote on half of the deal she struck with Brussels.

The Commons considered the withdrawal agreement, the legally binding “divorce deal” and covers the U.K.’s exit from the EU.

It contains proposals for the controversial Northern Irish backstop which is intended as an insurance policy to prevent the return of a hard border on the island of Ireland.

And it deals with issues like the financial settlement and citizens’ rights after withdrawal.

MPs did vote on the political declaration element which is non-legally binding and looks at the future relationship Britain will have with the bloc.

The previous two ‘meaningful votes’ by MPs have been on the two documents combined as one package.

Downing Street hoped the tactic would enable MPs who were opposed to the political declaration but supported the withdrawal agreement to vote with the government today.