A major Conservative Party donor is calling on the prime minister to step down as a former party chairman reveals himself as the leader of a rebellious group of MPs advocating for a new leader.

Charlie Mullins, the founder of Pimlico Plumbers, who has donated £50,000 to the Tories, said Theresa May is being undermined and “bullied” by Foreign Secretary Boris Johnson. He told The Guardian:

“She has got to go for her own sake. It is getting embarrassing. If this was a boxing match, the fight would have been stopped.

“She has been put in a position where she is being bullied, she is being intimidated, they are making her life hell. These are Conservative people who are destroying this woman and it needs to stop.”

Mr. Mullins, who funded Gina Miller’s Article 50 High Court challenge, spent £30,000 on a stall at this year’s Conservative Party conference where Mrs. May gave a “disastrous” speech. He said Mr. Johnson had been successfully undermining the prime minister.

“She is a broken woman. They are setting her up,” he said. “Boris is not a fool. He knows what he is doing.

“Boris is knocking her at every opportunity he gets because he wants to be prime minister. Boris has been a big part of destroying this woman.”

Former Conservative Party Chairman Grant Shapps has told Sky News "one or two cabinet members privately agree" the PM should resign pic.twitter.com/46I5vmiQhP — Sky News (@SkyNews) October 6, 2017

The donor’s intervention comes as Grant Shapps, the former Conservative Party chairman who resigned following the Tatler Tory scandal, claimed that 30 MPs and “one or two” cabinet ministers had agreed to sign a letter calling on Mrs. May to step down.

Under party rules, 48 Tory MPs can trigger a leadership contest by notifying the chairman of the 1922 committee.

Mr. Shapps told Sky News that his list of discontented MPs existed “long before” the party met in Manchester and that Downing Street “pleaded” with him not to go public earlier.

He said five former cabinet ministers, one former minister and “quite a lot of the backbenchers” from both Remain and Leave sides wanted Mrs. May gone, and that the list was “growing”.

“We think May is a decent person doing her best – but she led us into an election with that result,” he said.