The embattled Commons Speaker issued a defiant message to his critics yesterday, saying that he would remain at least until the autumn to take personal charge of overhauling MPs’ expenses.

In passionate remarks in the Commons, Michael Martin told fellow MPs that only they could remove him from the duties they had assigned to him.

His remarks were ostensibly about a review of Commons allowances, but his clear implication was that he was determined not to let media criticism force his resignation as Speaker. Mr Martin’s intervention came as Labour MPs, led by Gordon Brown, rallied to his support, with one accusing the media of attempting a coup to remove the Speaker. The show of backing from ministers and Labour backbenchers will ease the immediate pressure on Mr Martin, who faced calls to resign after Mike Granatt, his spokesman, stood down, saying that he was misled over £4,000 in taxi fares claimed by the Speaker’s wife.

Hopes among his critics that he would use a lull in press attacks on him to consider his future and quit by the summer suffered a setback, however, with Mr Martin’s own bullish comments. David Winnick, an independent-minded Labour MP, urged the Speaker in the Commons to show greater urgency in a review of MPs’ allowances, which is not due to report until the autumn. This was set up after the scandal over the Tory MP Derek Conway, who used a Commons staff allowance to pay his student son £12,000 a year and large bonuses for “all but invisible” research.

Mr Martin retorted: “Unanimously, including you, this House agreed to put this matter to the Members’ Estimate Committee, which I chair. This House has charged me with a responsibility and I will carry out that duty until this House decides otherwise, and that is a good thing for the reputation of this House.”

Earlier, the Speaker was cheered by MPs as the sitting began and, grinning, paused to tell them: “Thank you very much.” Outside the chamber there were further signs of Labour MPs closing ranks behind Mr Martin, who was a Labour backbencher and trade unionist before renouncing party allegiance on his election as Speaker in 2000.

There was some relief for Mr Martin yesterday as the Parliamentary Commissioner for Standards, John Lyon, announced that he would not conduct an inquiry into the Speaker’s transfer of air miles to members of his family.

Criticism persisted, however, with Clare Short, the former Cabinet minister and now independent MP, saying that he was the wrong person to chair a study of MPs’ expenses and urging him to stand down at the next general election. Ms Short told the BBC One Politics Show: “I think he should not be in charge or chairing a review of expenses. I mean, he is also an MP and he also applies for the expenses and now there are also suggestions of not breaking the rules, but stretching them.” She added: “I think it would be a good idea if he didn’t stand next time.”

Mr Brown set the tone for moves to shore up the Speaker’s position, with a terse statement during a visit to South London: “This is a matter for the House of Commons. Michael Martin has been a very, very good Speaker.”

His support was echoed by Alan Johnson, the Health Secretary, who complained of “open season” on the Speaker, and by Nick Clegg, the Lib Dem leader, who spoke of a “witch-hunt”. Mr Clegg was more guarded, saying that Mr Martin would have to answer allegations against him and that the controversy highlighted the need for an “utter overhaul” of MPs’ expenses and allowances.

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