Tony Blair has been urged to quit as prime minister early into his third term, days after Labour's election win.
Tony Blair has faced strong criticism over the Iraq war
Despite securing an historic third victory, the government's Commons majority was slashed from 161 to 67.
Several Labour MPs have described Mr Blair as a "liability", among them ex-Foreign Secretary Robin Cook.
However, senior party figures including David Blunkett and Peter Hain have rallied in support of Mr Blair, urging MPs to "get behind" their leader.
Downing Street has said there is "no change" from Mr Blair's statement last year that he would serve a full third term.
Robin Cook (Livingston)
Frank Dobson (Holborn and St Pancras)
Frank Field (Birkenhead)
Glenda Jackson (Hampstead and Highgate)
Desmond Turner (Brighton Kemptown)
John Austin (Erith and Thamesmead)
Jeremy Corbyn (Islington North)
Ian Davidson (Glasgow South West)
John McDonnell (Hayes and Harlington)
Bob Wareing (Liverpool West Derby)
Some MPs have suggested the prime minister should step down within a year to 18 months, with Chancellor Gordon Brown tipped as successor.
Mr Cook, who resigned from the Cabinet in protest at the Iraq war, told BBC1's Politics Show that Labour had won this election despite rather than because of Mr Blair.
The prime minister should be respected for having delivered two landslide election wins, he said, but it was now time for him to consider his future.
"The question Tony Blair should be reflecting on this weekend is having achieved this, having secured his place in the history of the Labour Party and the history of Britain, whether now might be a better time to let a new leader in who could then achieve the unity we need if we are going to go forward," he said.
Frank Dobson, who served as health secretary in Mr Blair's first Cabinet, told GMTV's Sunday programme the prime minister had been an "enormous liability" in this poll.
"I don't think we can go into important local elections next year... with Tony Blair as leader and expect to keep many of the councillors we've got now," he said.
John Austin, MP for Erith and Thamesmead, told The Sunday Times: "You can't beat about the bush. Blair was a negative factor on the doorstep, time and time and time again."
Work and Pensions Secretary David Blunkett
Northern Ireland Secretary Peter Hain
Culture Secretary Tessa Jowell
Jeremy Corbyn, MP for Islington North and a fierce critic of the Iraq war, predicted Mr Blair could be out of Downing Street within a year.
He told Channel 4's Morgan and Platell Programme: "I think he might well decide that the end of the G8 presidency (at the end of 2005) is the time to go. I don't think he would want to go in the middle of it."
Desmond Turner, the Brighton Kemptown MP, said: "It would be nice to see Brown crowned as early as the next party conference."
However ex-Labour minister and government critic Frank Field warned "gang warfare" between Blairite and Brownite factions could lead some MPs to look elsewhere for leadership contenders.
He dismissed Mr Blair's reshuffle as "like a Cabinet for Toy Town" and lacking "substantial" figures apart from Mr Blunkett.
Mr Field said: "He [Mr Blair] is clearly the best we've ever had at winning elections. The trouble with that of course is what we do after we've won an election."
Mr Blunkett, the new Work and Pensions Secretary, told the BBC's Breakfast with Frost the Iraq war had been a "major factor" in eroding confidence in the prime minister, but people had to move on.
"We now - all of us - have to build that confidence behind our prime minister who, after all, not only got a historic third term but got the kind of majority in that third term that we expected in 1997."
Mr Blunkett urged MPs to back the manifesto on which they were elected and "get stuck in... and deliver to the British people".
Otherwise, he said, they were being "as self-indulgent as the better-off who voted Lib Dem".
Culture Secretary Tessa Jowell also defended the prime minister, saying "serving a full term doesn't mean leaving office after a year or two".
The new Northern Ireland Secretary Peter Hain said the idea the public would welcome Mr Blair's immediate replacement as leader was "fantasy".
Mr Blair's ex-communications director Alastair Campbell said people underestimated the prime minister's achievement in securing a third election victory.
The Observer reports that within Mr Blair's own private circle the timetable being discussed would involve him triggering a party leadership contest in July 2008.
He would remain as prime minister while the succession was resolved, allowing the new leader to take over that autumn.
A Downing Street spokesman declined to comment other than to point to Mr Blair's statement of last September in which he said that if re-elected he would serve a full third term.
"There has been no change," he said.
Former "Blair babe" Helen Clark has confirmed she is quitting Labour and applying to join the Conservatives in protest at Tony Blair's style of government.
Mrs Clark, who lost her Peterborough seat to Tory candidate Stewart Jackson on Thursday, said she believed that Conservatives, under a new leader, would be a more inclusive and effective party.