Double trouble for Boris Johnson as he could face two leadership challenges in six months

Boris Johnson could face a second leadership challenge within six months – even if he were to survive one in the coming weeks – under "live" proposals being discussed by backbench Tories.

With Sue Gray's report into Downing Street parties now expected as soon as Wednesday, there is renewed speculation that her findings will trigger a wave of letters of no confidence in the Prime Minister.

Should the threshold of 54 letters be hit, allies of Mr Johnson have said they are confident that he could survive the subsequent confidence vote.

A total of 181 MPs – more than half the parliamentary party – would need to vote against the Prime Minister for him to be removed from office.

However, senior Conservative sources have revealed that even if he were to survive, he is unlikely to be immune from another challenge for 12 months, as is currently the case.

Instead, two insiders said there was "live discussion" among the executive members of the 1922 Committee of backbench Tory MPs over whether the grace period should be halved to six months.

Should the committee decide to change the rules, the insiders said it was likely that the threshold required to trigger a second ballot would double, with the number of MPs required to submit letters increasing from 15 per cent to 30 per cent.

Similar discussions are also understood to have occurred after Theresa May survived a confidence vote in 2018. The change was ultimately deemed unnecessary when she resigned on May 24 2019, a day after the Tories had suffered a disastrous set of results in the European elections.

"These conversations take place every time there is a crisis of confidence," a senior source said on Friday. "The issue is that the 1922's job is to represent the party. And if the PM were to win and they [letters] were to flood in again, then it's not clear what would happen. Anyone assuming that there is going to be a 12-month period is mistaken.”

A second source said: "The situation with Mrs May was that the rule change wasn't made because we didn't need to – that is the distinction."