THERESA May has said she will contest a leadership challenge "with everything I've got".

The Prime Minister was speaking after it was confirmed enough Tory MPs have requested a vote of confidence in her to trigger a contest.

There was speculation overnight that the 48-letter limit - enough to trigger a vote under party rules - had been reached and it was confirmed by chairman of the backbench 1922 Committee, Sir Graham Brady, this morning.

READ MORE: Somerset MPs speak out ahead of no-confidence vote for the Prime Minister

Ministers have so far emerged backing the PM, in response to those who are keen to see her stand down, including Somerset MP Jacob Rees-Mogg, who tweeted that it was 'time for Mrs May to resign'. 

Conservative former Cabinet minister Owen Paterson told BBC Radio 4's Today programme he had "not found it at all easy" writing his letter, but said: "I just I'm afraid think she's no longer the right person to lead us through this difficult period."

He speculated there could be a new PM by mid-January, in the event of a leadership challenge.

Sir Graham said a ballot would be held between 6pm and 8pm on Wednesday in the Commons.

He added in a statement: "The votes will be counted immediately afterwards and the result will be announced as soon as possible in the evening."

Moments after news of the vote was announced, Foreign Secretary Jeremy Hunt tweeted: "I am backing @theresa_may tonight. Being PM most difficult job imaginable right now and the last thing the country needs is a damaging and long leadership contest.

"Brexit was never going to be easy but she is the best person to make sure we actually leave the EU on March 29," he added.