David Cameron has increased the chances of facing a post-election attempt to oust him as party leader by announcing that he would not seek a third term as Prime Minister, Conservative MPs have warned.
Backbench critics, already planning to force a vote of confidence in Mr Cameron if he fails to win an overall majority, said their task of getting the required 15% of Tory MPs to trigger such a vote would be made easier by his surprise remarks.
Another option is to turn the vote Mr Cameron has promised his MPs if he proposes a second coalition into a vote of confidence on his leadership, in the hope of defeating it and forcing his resignation.
Tory MPs claimed yesterday that Mr Cameron's comments in a BBC interview on Monday had weakened his authority and diverted the party's disciplined election campaign based on the economy.
One senior MP said the Prime Minister may have accidentally brought forward his departure date. "If the election result is not good enough, some people will now say, 'He's going before 2020 anyway; we might as well go for him now'," he claimed.
"This makes it easier to have a day of reckoning immediately after the election. He has made himself more vulnerable."
Another senior Tory said the Prime Minister had given his potential successors the go-ahead to start campaigning by naming Theresa May, George Osborne and Boris Johnson as the party's possible next leader. "He has made it acceptable to form armed camps and fan clubs. If he remains in power, he has ensured a five-year Westminster soap opera and has even supplied the main characters," said the MP.
Some Tory MPs think Mr Cameron may have damaged the chances of Ms May, Mr Osborne and Mr Johnson by name-checking them. They believe that MPs, who choose a shortlist of two leadership rivals, and party members, who make the final choice, may now be more likely to elect someone younger. And Mr Cameron may have alienated two potential rising stars by not naming them: Sajid Javid, the Culture Secretary, and Elizabeth Truss, the Environment Secretary.