One MP said: "Davis is playing games to try to force Boris's hand. It's not going to work This is too big a moment to play games. All this speculation just undermines Theresa. The party needs to get behind her."

Another ally of Mr Johnson said: "People have short term memories. They see David as a steady hand but forget he lost to David Cameron in 2005 and has previously resigned.

"He's also the man that pushed the Prime Minister into holding a snap election in the first place.

"Age is not a barrier but he is nearly 70. You have got to look at that as a factor."

During the 2005 Tory leadership campaign Mr Davis was accused of sexism after he posed alongside two female supporters wearing t-shirts with the logo "It's DD for me".