TORY backbench boss Sir Graham Brady has begged angry MPs for no more formal demands for a leadership contest — sparking suspicion a challenge on Theresa May is imminent.

A no confidence vote in the Conservative leader is automatically triggered if Sir Graham receives 48 letters, which is 15% of the parliamentary party.

2 Top Tory Graham Brady is concerned about another leadership challenge to Theresa May Credit: PA

One senior backbencher told The Sun the top Tory was “ashen faced” at the prospect of getting one more letter recently – which he has intimated could spark a bitter leadership election and plunge Brexit talks into chaos.

The party grandee’s terrified reaction suggests the number of letters he has already received may now have reached the mid 40s, as anger with “dull, dull, dull” Theresa May spirals on the Tory benches.

The Sun has also learnt that Brady has told colleagues mulling over whether to send a letter recently to “be careful” and think of the “consequences” before putting pen to paper.

Nicknamed “The Men In Grey Suits”, the powerful backbench 1922 Committee must notify Downing Street within 24 hours that the critical threshold for a confidence vote has been met.

2 Theresa May has been accused of being too timid to take big decisions Credit: AFP

Tory sources claim 30 MPs had written in after the PM’s election disaster last year, with a further flurry of concern after her gaffe-strewn party conference in October and this year’s badly received reshuffle.

Given the crucial role Brady holds determining her future, Mrs May raised eyebrows in Westminster by knighting him in the New Year’s Honours list earlier this month.

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Last night Sir Graham declined to comment, but a Committee insider insisted that the Chairman’s role was “passive” and he would not urge MPs either way.

The source said it was was still the view “of the majority of Conservative MPs that now is not the right time for a change of leader” amid fears it would lead to a fresh General Election.

But they added Sir Graham could advise colleagues should they come to him and ask.