Theresa May’s critics in the Conservative party, who want to oust her, have described her decision to accept a delay to Brexit until October 31 as a “Halloween horror”.

Halloween, when people dress up as monsters and children knock on doors demanding money with menaces, falls on October 31.

“Theresa May faces renewed pressure to resign after agreeing Halloween delay date with the EU,” was Thursday’s headline in the London Evening Standard, which is edited by George Osborne, chancellor under David Cameron but sacked when May took over.

The Daily Mail’s headline was, “It’s a Brexit Halloween nightmare,” with several cartoonists show Brexit and May disappearing down a black hole.

Calling on May to stand down before the Conservative Party conference in September, former Tory leader Iain Duncan Smith said: “The whole thing is an utter car crash... I think the cabinet has to have a moment with the Prime Minister and say, ‘This can’t go on, I’m afraid, it really can’t go on.’ ”

Tory MPs cannot try and force May out via a vote of no confidence until December. But rebels will try to exploit a loophole in the Conservative party constitution which allows rules to be changed with a petition signed by 10,000 members.

Former Brexit secretary David Davis said pressure on May to quit as Prime Minister will increase, telling the BBC on Thursday: “The pressure on her to go will increase dramatically, I suspect, now. Whether it will come to anything — who knows?”

Asked if May could still be Prime Minister at the time of the Tory conference in autumn, Davis replied: “I think it is going to be difficult because by that time we will have had a European election which will become a plebiscite, really, on Brexit.”

BBC political editor Laura Kuenssberg said one government minister had told her that the delay could mean a Conservative party leadership contest after Easter, with potentially a new Prime Minister by June.

The British Prime Minister had sought to delay Brexit from April 12 to June 30 but the majority of the 27 leaders of the EU members meeting at a summit in Brussels on Wednesday wanted to give the UK until the end of the year or even early 2020 to find a consensus over the withdrawal agreement in the House of Commons.

After five hours of talks which ended in the early hours of Thursday, October 31 was the compromise date.

But the UK will have to part in elections to the European Parliament next month at a cost of over £100 million to the British taxpayer even though it is leaving the EU.

Failure to abide by this requirement will lead to the UK’s expulsion from the EU on June 1.

While May was made to wait outside, the EU leaders enjoyed dinner consisting of warm scallop salad, followed by loin of cod with brown shrimps and mini mushroom arancini, and iced macadamia nut parfait as dessert. There was a suggestion that the British Prime Minister had to make do with sandwiches.

After the summit ended at about 2am, May acknowledged: “I know that there is huge frustration from many people that I had to request this extension.”

She blamed MPs for the delay: “I sincerely regret the fact that I have not yet been able to persuade parliament to approve a deal which would allow the UK to leave in a smooth and orderly way.”

She pointed out that “vitally the EU have agreed that the extension can be terminated when the withdrawal agreement has been ratified, which was my key request of my fellow leaders.

“For example, this means that if we are able to pass a deal in the first three weeks of May, we will not have to take part in European elections and will officially leave the EU on Saturday June 1.”

European Council president Donald Tusk, who steps down on October 31, said his “message to British friends” was “please do not waste this time”.