The European Commissioner for External Relations and former Northern Ireland Secretary, Mr Chris Patten, has warned the Conservative Party that future success requires it to prove itself a broad church "able to accommodate the views of Michael Portillo and Kenneth Clarke".
But a question mark continued to hang over Mr Portillo's intentions last night, as Ms Ann Widdecombe effectively became the first candidate to declare in the battle to succeed Mr William Hague.
In the classic political manner, Ms Widdecombe told Sir David Frost that she was under pressure to run but had still to "take soundings" among colleagues before reaching her decision.
But there was no doubt at Westminster that her decision was already made as returning MPs faced the prospect of two months' bitter warfare for the heart and soul of the Conservative Party.
Ms Widdecombe's hopes took an early knock, however, with a Mail on Sunday report that the defeated Mr Hague is preparing to back his shadow defence spokesman, Mr Iain Duncan Smith, in a determined effort to block Mr Portillo.
Rejecting claims that Mr Duncan Smith - who might well expect the endorsement of Lady Thatcher and Lord Tebbit - was "too right-wing", friends were quoted as saying: "Iain is a fully paid-up member of the human race, which is more than can be said of some of the candidates."
And a third figure from the Tory right, Mr David Davis, is also said to be canvassing support in what could still become a party blood-letting over the "socially inclusive" agenda of the Mark II Portillo.
It remained unclear, meanwhile, whether Mr Clarke - according to the opinion polls his party's most popular asset - would settle for the role of "kingmaker" or join the contest himself.
Mr Clarke has reportedly ruled out standing on a joint ticket with Mr Portillo, amid continuing speculation that he might join a Portillo shadow cabinet in return for freedom to campaign for a Yes vote in the expected referendum on British membership of the euro.
However, the Sunday Telegraph suggested Mr Clarke might declare his own candidacy soon after a meeting today of officers of the Mainstream group of Conservative MPs. Supporters of Mr Clarke are said to regard Mr Michael Heseltine's forceful endorsement on Friday as evidence that he may have already persuaded the former Chancellor to stand.
Mr Portillo spent the weekend after Labour's second landslide victory reflecting in the Moroccan sunshine.
Some of his supporters appear convinced he will seek the leadership and that an alliance with Mr Clarke would effectively end the contest before it gets properly under way.
However, other admirers say his wife is not enthusiastic and that the couple would have to weigh the effect of Mr Portillo's revelations about his earlier private life.
Still others question whether Mr Portillo (48) - who famously prefers government to politics - would want to commit himself to what appears a certain two-term project to take the Tories from opposition to government.
Given the scale of voter apathy in last week's election, Mr Patten rejected that assumption yesterday - while acknowledging that it would be extremely difficult to return to government next time.
But he was clear in his view that "a successful Conservative Party has to be able to accommodate the views of Michael Portillo and Kenneth Clarke. It has got to be a broad church, not a narrow sect".
Ms Widdecombe yesterday attempted to broaden her appeal beyond her party's "moral authoritarian tendency".
She said she would be prepared to appoint pro-Europeans like Mr Clarke to her shadow cabinet.
"You cannot just have a collection of Colonel Blimps," she said.