Blair was dubbed "reckless" by Short
Clare Short has "pretty well burned her boats" with the Labour Party and is now playing a role sketched out for her by Tony Blair, a fellow Birmingham MP has told the BBC.
Labour left-winger Lynne Jones said she expected the international development secretary to be sacked when she no longer appeared "useful" to Tony Blair.
The comments came after Ms Short questioned whether civilian deaths were a price worth paying for overthrowing Saddam Hussein.
She also criticised preparations for dealing with civil disorder as inadequate, saying: "The likelihood of very rapid regime collapse, and then the complete collapse of all public services, and the kind of disorder we've had, clearly we weren't prepared for.
"We should have done better."
The comments come six weeks after Ms Short said she would quit her cabinet post if the UK went to war with Iraq without UN backing. She subsequently decided not to go.
Ms Jones told BBC Radio 4's World at One: "It's fairly typical Clare that she has been public about her concerns.
"I think that's probably the role that Tony Blair has put her up to and she is carrying out the role she feels she has to play."
I'm just saying that is how she feels. She feels she has that role to play
She added: "I don't think she's connecting with people in the Labour Party.
"I think the public may be somewhat reassured by Clare's statements that the government is apparently giving priority to the humanitarian situation, but as far as the Labour Party is concerned, I think she has pretty well burned her boats.
"Those who supported the war will be angry that she is still apparently seeming to be criticising, and those who were always concerned about the aftermath of the war and the justification of the war will wonder why she felt able to go along with it if she is now so concerned about the humanitarian situation."
Asked if it was "cynical" to suggest Mr Blair was encouraging Ms Short to act against her conscience for PR purposes, Ms Jones said: "I'm just saying that is how she feels. She feels she has that role to play."
Ms Jones speculated that Mr Blair had felt he had to keep Ms Short in her post because he was faced with the resignation of fellow cabinet minister Robin Cook.
Speaking to foreign journalists at the Foreign Press Association (FPA) on Tuesday Ms Short said there was still deep concern among Labour MPs about the situation in Iraq, despite the defeat of Saddam Hussein.
But Ms Short, who had branded Mr Blair as "deeply reckless" in joining the US-led action, insisted the party was not split.
It is too early to decide what the long term effect on
the prime minister is
At the FPA news conference, Ms Short refused to comment on whether she still
thought the war had been reckless.
But she added: "I am pleased to be a part of a party that is deeply
troubled by a war.
"It is too early to decide what the long term effect on
the prime minister is."
The prime minister's policy on Iraq caused him the biggest revolt of his career in the House of Commons, with 138 Labour MPs voting against the government on military action.
Another senior Cabinet minister, Robin Cook, and two junior ministers
resigned over the crisis, plus a number of parliamentary private secretaries.
But Mr Blair retained the backing of two-thirds of his party and, helped by the Conservative Party, won
support for a war by a comfortable margin.