The prospective show of solidarity coincides with the renewed resolve of Mr Major to relinquish office at a time of his choosing, in spite of the expected drubbing in today's local elections, and next month's European Parliament contests. That leaves dissatisfied Tory backbenchers little choice but to bring the issue to a head by activating a stalking-horse challenge.
One-tenth of the parliamentary party - 34 MPs - have to inform the chairman of the 1922 backbench committee, Sir Marcus Fox, that they want a contest, although only the nominee and seconder have to be named publicly.
While a summer reshuffle could bring changes among whips as well as ministers, continuing loyalty to the Prime Minister is expected to prompt at least eight of the present 14 to support him in public - in contradiction of the convention that they remain neutral.
That rule was rigidly adhered to by the then Chief Whip, Humphrey Atkins, during the 1975 contest when Margaret Thatcher emerged as a successful stalking horse challenger to Edward Heath.
In 1989, Tim Renton, the Chief Whip, preserved neutrality during the challenge to Mrs Thatcher by the former MP for Clywd North West, Sir Anthony Meyer.
The deputy Chief Whip, Tristan Garel-Jones, later a Foreign Office minister, stood down from office for the duration of the contest to help run a behind-the-scenes operation in support of Mrs Thatcher.
One whip said: 'We know about the rule but a number of us would be prepared to break it. I think John Major is the right man.' Mr Major might ultimately enjoy the active support of all Government Whips because those who have expressed no allegiance could be expected eventually to go with the majority.
Failure to win the positive support of 50 MPs would be bad enough for Mr Major. If opponents or abstainers reached 100 he would have little option but to stand down, leading to an open contest between contenders such as Michael Heseltine and Kenneth Clarke.
A handful of MPs were even suggesting yesterday that an approach to Sir Marcus might be made soon after the European elections.
But that scenario was heavily discounted, even by Mr Major's critics. Alongside the latest rumblings that possibly 50 MPs would be happy to see him go, there were warnings yesterday that the 34 names might be difficult to mobilise in the final event.
Despite the rebuke of Michael Portillo, Chief Secretary to the Treasury, over policy on the single currency, there were suggestions from his supporters that Mr Major might have little choice but to eventually opt for a more Euro-sceptical line, in the interests of saving the party from an irretrievable split while, at the same time, securing his own future.Reuse content