Pulling out of Iraq now would be a "betrayal" of the sacrifices already made by UK troops, Tony Blair has said.
MPs want to debate the role of British troops in Iraq
He sidestepped growing calls for a full Commons debate on Iraq, saying he was happy to talk about it "at any time".
And he told MPs the strategy of only withdrawing troops when the Iraqis can "handle" security would not change.
"To do anything else would be a complete betrayal, not only of the Iraqi people but of all the sacrifices our armed forces have made," he said.
Speaking at prime minister's questions in the Commons, Mr Blair said the Iraqi people had the "chance of a proper functioning democracy and we should stick by them".
Senior MPs from all parties have called for a full Commons debate on Iraq in the wake of continuing violence and comments by army head General Sir Richard Dannatt.
Ex-Tory foreign secretary Sir Malcolm Rifkind's motion calling for a debate has been backed by SNP leader Alex Salmond, ex-Tory ministers Ken Clarke and Douglas Hogg, Lib Dems Michael Moore and Nick Harvey and former Labour minister - now independent - Clare Short.
They are pushing for an all day debate on Iraq - the first for two years.
It follows similar calls from Lib Dem leader Sir Menzies Campbell - who wants a vote on whether troops should pull out - and shadow foreign secretary William Hague.
A separate motion from Conservative MP, John Baron, says a debate is vital following warnings by Army chief General Sir Richard Dannatt, that the presence of British troops was exacerbating security problems in Iraq.
His motion is signed by former Labour ministers Frank Field and Kate Hoey along with Conservative and Lib Dem MPs.
With mounting pressure in the UK and US for a reappraisal of tactics in Iraq, Plaid Cymru MP Adam Price did secure a debate on the issue, but that was in Westminster Hall, and not the main Commons chamber.
That debate, earlier on Wednesday, became heated with Armed Forces Minister Adam Ingram branded a "disgrace" after suggesting "some would say" the anti-war movement was "pro-dictator".
There were shouts of "disgrace" from SNP leader Alex Salmond, Labour's Jeremy Corbyn and Plaid Cymru's Adam Price.
Mr Ingram also signalled a possible role for Iran and Syria in Iraq's future.
He told MPs "those who are part of the problem must be part of the solution - otherwise they remain part of the problem".
Meanwhile US Defence Secretary Donald Rumsfeld is among members of the Bush administration who have been speaking out to try to convince voters that success can be achieved in Iraq.
President Bush's handling of the Iraq crisis has become a major issue in the elections next month for Congress, with predictions that his Republican party could lose control of the Senate and House of Representatives.
A review of American options is being carried out by former US Secretary of State James Baker - to be published after the 7 November elections.