Theresa May clinging on as Tory leader amid rumours a no confidence vote is imminent

Theresa May's premiership is hanging by a thread as Tory MPs are expected to launch a formal leadership challenge, having reportedly secured enough letters of no confidence to trigger a ballot.

It was reported on Tuesday night Sir Graham Brady, chairman of the Conservative committee that overseas leadership challenges, has requested a meeting with the PM on Wednesday afternoon to inform her he has received the 48 letters of no confidence needed to spark a vote.

Downing Street sources said they had not been told by Sir Graham if the threshold had been reached, but would not confirm if a meeting with the MP was scheduled for Wednesday afternoon.

If 48 letters had been received May could be subjected to a vote of confidence by her MPs before the end of the week.

If she loses, May would be out as Prime Minister and unable to stand in the subsequent leadership contest.

Should she win, even by one vote, the Conservatives would not be able to challenge her for another year.

Rumours May was set to face a challenge to her leadership gathered pace on Tuesday evening, culminating in former cabinet minister Owen Paterson submitting a letter.

Paterson had previously acted as a bridge between Brexiters and Downing Street, and won praise from May for suggesting alternative routes to escaping the controversial backstop arrangement which could see the UK locked in the EU’s customs union.

May returned to the UK on Tuesday night after a whistle stop tour of European cities – visiting Berlin, Brussels and The Hague – in an attempt to keep her much derided withdrawal deal alive.

She was set to travel to Dublin to meet Irish Taoiseach Leo Varadkar on Wednesday afternoon in a bid to get further assurances over the temporary nature of the so-called ‘backstop’ in the Brexit deal.

Speaking after meeting Tusk and European Commission president Jean-Claude Juncker, May insisted the backstop would stay in the withdrawal agreement.

She said: “The backstop is a necessary guarantee for the people of Northern Ireland and whatever outcome you want, whatever relationship you want with Europe in the future, there’s no deal available that doesn’t have the backstop within it.

“We don’t want the backstop to be used and if it is we want to be certain that it is only temporary and it is those assurances I will be seeking from fellow leaders over the coming days.”

May added: “I have seen a shared determination to deal with this issue.”

While Downing Street insisted nothing is off the table when it comes to discussions with her EU counterparts to make the deal more popular with MPs – including reopening talks on the withdrawal agreement – German Chancellor Angela Merkel appeared to shoot down that possibility.

According to reports she told a meeting of her own MPs there was “no way to change” the agreement after meeting May.

If that view is echoed across the EU, May faces a repeat of the battle which forced her to pull the vote, as many MPs want to see the backstop removed entirely from the legal text.

In a debate on the decision to delay the vote, DUP MP Gavin Robinson – part of the group which props up May’s government – said: “Unless there is a fundamental alteration to the text of the withdrawal agreement and to the advice given by the Attorney General himself, it simply will not suffice.”