Theresa May is fighting to save her Brexit deal – and potentially her premiership – amid renewed claims Tory MPs are close to forcing a vote of no confidence in her leadership.

Westminster was awash with rumours that rebels were on the brink of – or had actually reached – the threshold of 48 letters needed to trigger a vote.

Former cabinet minister Owen Paterson became the latest MP to declare he had submitted a letter to the chairman of the backbench 1922 Committee, Sir Graham Brady.

It followed reports of a wave of new letters amid anger at the way Mrs May dramatically put on hold the crunch Commons vote on her Brexit deal after admitting she was heading for a heavy defeat.

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Chief Whip Julian Smith leaves Downing Street (Victoria Jones/PA)

Speculation that a challenge could be imminent was fuelled after chief whip Julian Smith and Conservative Party chairman Brandon Lewis were seen leaving No 10 following late-night consultations on Tuesday.

And unconfirmed reports suggested Sir Graham has asked to meet Mrs May after Prime Minister’s Questions on Wednesday afternoon.

In his letter, published in The Daily Telegraph, Mr Paterson said Mrs May’s conduct of the Brexit negotiations had “eroded trust in the Government, to the point where I and many others can no longer take the Prime Minister at her word”.

The former Northern Ireland secretary and prominent Brexiteer said she had become a “blockage” to an agreement which Parliament and the country could support.

“She has repeatedly said ‘no deal is better than a bad deal’, but it is clear her objective was to secure a deal at any cost,” he wrote.

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Owen Paterson has submitted a letter calling for a vote of no confidence (Victoria Jones/PA)

In the meantime, the Prime Minister is set to continue her whistle stop tour of European capitals as she seeks to win additional assurances on the Northern Ireland “backstop” which she hopes will persuade critics to back her deal.

However, given the scale of the opposition, it is unclear anything she could bring back would be enough to get it through the Commons

She will fly out on Wednesday evening to Dublin for talks with the Taoiseach Leo Varadkar, before travelling on to Brussels for a summit of EU leaders starting on Thursday.

Her visit follows meetings on Tuesday with German chancellor Angela Merkel, Dutch prime minister Mark Rutte, European Council president Donald Tusk and European Commission president Jean-Claude Juncker.

Before heading to Ireland, she is due to chair the weekly meeting of the Cabinet – postponed from Tuesday – as well as holding talks with DUP leader Arlene Foster, whose party props up her minority Government in the Commons.

Ahead of their meeting, Mrs Foster underlined the precarious nature of Mrs May’s position as she reaffirmed the DUP’s implacable opposition to the backstop which, it says, impose a “border in the Irish Sea” between Northern Ireland and the rest of the UK.

“We need to remove the backstop. This has been our message from the day a backstop was conceived,” she said.

“It is not a case of repackaging or varnishing. Tinkering around the edges will not work. Assurances or reassurances are not what we are seeking.

“We want to see to see the Withdrawal Agreement fundamentally changed.”

Following his talks with Mrs May, Mr Tusk described their meeting as “long and frank”, adding: “Clear that EU27 wants to help. The question is how.”

Mr Juncker insisted that while there was “no room whatsoever for renegotiation” of the Withdrawal Agreement, there was scope for “further clarifications and further interpretations”.

Speaking to reporters in Brussels, Mrs May acknowledged any deal with the EU would have to include a backstop to ensure there could be no return of a hard border between Northern Ireland and the Republic.

“Whatever outcome we want, whatever relationship we want with the European Union in future, there is no deal available that doesn’t have a backstop within it,” she said.

“But we don’t want the backstop to be used and if it is, we want to be certain it is only temporary.

“It is those assurances that I will be seeking from fellow leaders over the coming days.”