THERESA May has insisted she has the “full support” of her cabinet, despite the ringleader of a plot against her claiming even some of her closest colleagues now want her to quit.

As senior Tories fought publicly over her future, with one former party chair telling another to “shut up”, the Prime Minister maintained she was providing “calm leadership”.

A downward spiral of infighting now threatens to undermine her authority even more.

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Mrs May’s position has looked increasingly fragile since her showpiece conference speech on Wednesday descended into chaos, with a prankster, coughing fits and a collapsing set.

Grant Shapps, who was Tory chairman from 2012 to 2015, was outed on Friday as the leader of a backbench plot of around 30 MPs who want Mrs May to step down.

The group, said to include five former ministers, hopes to send a delegation to Mrs May to tell her she has lost her authority and must go for the sake of the party.

The direct approach is because the plotters are short of the 48 names needed to trigger a formal confidence vote via a letter to the chair of the Tory backbench 1922 committee.

Ms Shapps said he had been unmasked by Tory whips, who had leaked his name to a newspaper in an attempt to “smoke out” fellow rebels.

He told BBC Radio 4’s Today programme there was a “broad spread” of MPs in the group, both Remainers and Brexiters, and some cabinet ministers privately agreed with them.

He said: “A growing number of my colleagues, we realise that the solution isn't to bury our heads in the sand and just hope things will get better. It never worked out for [Gordon] Brown or [John] Major and I don't think it is going to work out here either."

READ MORE: Fresh plot to oust the Prime Minister

Speaking to reporters later in her Maidenhead constituency, Mrs May brushed aside the comments, and said she planned to carry with business as usual.

She said: “What I think is necessary for the country now, what the country needs, is calm leadership. That’s exactly what I’m providing, and I’m providing that with the full support of my cabinet.”

Other senior Tories launched a wave of attacks on Mr Shapps.

Charles Walker, vice chairman of the 1922 committee, called the plot “a coalition of the disappointed" who had been pased over for promotion.

He said: "Number 10 must be delighted to learn that it is Grant Shapps leading this alleged coup. Grant has many talents but the one thing he doesn't have is a following in the party. I really think this is now just going to fizzle out.”

Baroness Sayeeda Warsi, who was Tory chair before Mr Shapps, said: “My message to Grant is, really, shut up. If there’s one thing Grant has done, if there’s one positive that’s come out of this, it’s that he has united the party and large sections of the public behind Theresa May. It’s time for politicians to put their personal interests to one side and get on with the job the public has elected us to do.”

Tory MP James Cleverly tweeted: "I've always liked @grantshapps but he really is doing himself, the party, and (most importantly) the country no favours at all. Just stop".

Veteran Tory MP Michael Fabricant said: "I wouldn't buy a used car from one embittered colleague - let alone take advice from him about who should be PM. Theresa May should remain."

Transport Minister Jesse Norman also posted on social media: "This is absolutely not what the country needs. The team needs to get behind the PM 100 per cent."

READ MORE: Sterling slips amid political jitters as Theresa May's future called into question

The volatility in the Tory party comes ahead of Mrs May meeting business leaders on Monday to reassure them the Brexit process is on track.

Chancellor Philip Hammond and Brexit Secretary David Davis will also meet Balfour Beatty, HSBC, Morgan Stanley, JCB, Vodafone, Aston Martin, Nestle and others in Downing Street.