Mr Clegg said the Speaker was 'a dogged defender of the way things are'
Nick Clegg has become the first party leader to call for the Commons speaker to resign in the midst of the expenses crisis gripping Parliament.
The Lib Dem leader said Michael Martin should make way as he was not the "right man" to lead much-needed reform.
The Speaker will make a statement on Monday and Labour MP Sir Stuart Bell says he expects him to say he will stay in the post until the next election.
This came as the Sunday Telegraph published more details of expenses.
The MPs highlighted in the newspaper's report, including former Conservative chief whip David Maclean and Labour whip Fraser Kemp, have defended their actions.
Conservative MP Douglas Carswell is table a motion of no confidence in the Speaker on Monday and says he has half a dozen signatures, including those of senior Conservative David Davis and a number of Labour and Lib Dem MPs.
The motion states that the Speaker has "failed to provide leadership" over the expenses scandal, has lost the confidence of the House of Commons and should step down.
It goes on to say that a successor should be chosen by a secret ballot of MPs.
Under parliamentary rules, the Speaker can either ignore the motion or ask for it to debated in government time.
Conservative MP Douglas Carswell: 'Change has to start with a new speaker'
Veteran Labour MP Sir Stuart Bell, an ally of the Speaker, said he believed Mr Martin would make it clear on Monday that he will stay on until the end of the Parliament to oversee reform of the expenses system.
It is also likely he will say he will step down from the post at the next general election - expected in May 2010 - in effort to end the row over his future.
Those calling for Mr Martin to go now did not reflect the majority of opinion in the Commons, Sir Stuart - who sits on the influential Commons Commission and Members Estimate Committee - told the BBC.
He said he did not believe Parliament would be prepared to "take such a step" to force him out.
The Speaker has come under increasing pressure from all sides for his handling of the expenses crisis.
In angry exchanges earlier this month, he criticised MPs who questioned Parliament's decision to ask the police to investigate the leaking of details of MP's expenses to the Daily Telegraph.
By becoming the most senior politician to call for the Speaker's resignation, Mr Clegg will dramatically increase the momentum behind moves to unseat him.
TEXT OF MR CARSWELL'S MOTION
That this House has no confidence in Mr Speaker and calls for him to step down; notes that Mr Speaker has failed to provide leadership in matters relating to honourable members' expenses; believes that a new Speaker urgently needed to be elected by secret ballot, free from manipulation by party whips and believes that a new Speaker should proceed to reform the House in such a way as to make it an effective legislature once again
Mr Clegg told the BBC's Andrew Marr Show that he was not seeking the Speaker's resignation "lightly or with any relish" but that it was clear that it was a necessary step to rebuild confidence in Parliament.
"I don't think he is the right man for the job of leading the renewal of Westminster that we need," he said. "We need a fresh start."
The Speaker was a "dogged defender of the status quo", Mr Clegg added, when what Parliament now needed was a radical reformer.
Mr Clegg said he had stood in the way of greater "transparency and accountability" in what MPs should receive.
The Commons authorities, of which the Speaker is the figurehead, blocked several requests to have expenses details released under Freedom of Information laws.
The BBC's political correspondent Iain Watson said Mr Clegg was breaking with convention by calling for the Speaker's departure and the move would be seen as highly controversial.
Labour MP Kate Hoey told the BBC on Sunday that she would sign a motion of no confidence.
"I don't think there is confidence there that he can lead us into this new era where we might begin to win back the confidence of the people," she said.
Foreign Secretary David Miliband said it was up to MPs to "come to their own view" about the issue and the government could not be seen to be "bullying" parliament over the Speaker's position.
But he said he did not believe Mr Martin "got it right" last Monday when he ticked off several MPs who questioned how the Commons authorities had acted over expenses.
Any move to unseat the Speaker would have to be supported by the Conservatives and commentators question whether they are willing to do this less than a year before the next election.
THE SPEAKER'S ROLE
The Speaker is the figurehead of the House of Commons, chairing debates, keeping order and calling on MPs to speak
Is elected by MPs in a Commons vote, traditionally remaining in the role until retirement or death and re-elected automatically after general elections
Michael Martin was elected following the retirement of Betty Boothroyd in 2000
But shadow foreign secretary William Hague said the issue needed to be settled urgently.
"This has clearly reached crisis point and has to be resolved immediately if the House of Commons is to go about its business and is to have confidence in it," he told Sky News.
However, he said the issue was a matter for Parliament and no government, nor aspiring government, should try to determine the outcome.
Labour backbencher Stephen Pound said he supported the Speaker and did not believe a "blood sacrifice" was the right way of dealing with the situation.
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