House of Commons Speaker Michael Martin called the leaders of the political parties to an urgent meeting on MPs' expenses today, as a motion of no confidence in him was tabled by a Conservative backbencher.
In an emergency statement to the Commons, Mr Martin said MPs should accept that they had let voters down "very badly indeed" and he was "profoundly sorry" for any contribution he may have made to the crisis.
His statement came just moments after Conservative leader David Cameron called for the immediate dissolution of Parliament to clear the way for a general election as soon as possible after the June 4 European and council polls.
Tory backbencher Douglas Carswell tabled a motion of no confidence in Mr Martin as Speaker, bearing the signatures of 15 MPs from the three major parties.
Other backbenchers echoed his call for the Speaker to go.
Mr Martin, calling on Mr Cameron, Prime Minister Gordon Brown and Liberal Democrat leader Nick Clegg to meet him within 48 hours, said: "We all bear a heavy responsibility for the terrible damage to the reputation of this House.
"We must do everything we possibly can to regain the trust and confidence of the people."
The Speaker said he wanted to say to the country: "We have let you down very badly indeed. We must all accept blame and to the extent that I have contributed to this situation, I'm profoundly sorry.
"Now each and every member, including myself, must work hard to retain their trust."
He said that as a matter of urgency and "within 48 hours, I'm calling the Prime Minister and party leaders, including minority parties, to meet with me and other members of the House of Commons Commission".
The Speaker went on: "I want discussion to centre on the Additional Costs (second homes) Allowance and on those matters that have caused greatest controversy and most anger with the public."
He said he wanted proposals brought forward to deal with the immediate crisis and went on: "In the meantime, I do urge all honourable members not to submit claims for approval."
But his statement did little to quell anger among MPs about his own role and did not address the issue of whether he would step down before the next election.
Tory MP Richard Shepherd urged that the motion of no confidence in Mr Martin should be debated, but the Speaker said that was a matter for the Government.
Speaking outside the chamber, Mr Carswell insisted Mr Martin was "not up to the job".
"If he had given that speech four or five, or even three years ago, there would at least have been something positive to be said," he told the BBC.
"But I am afraid it is simply not enough."
Mr Carswell went on: "The Government now needs to take stock of the situation. Is it prepared to limp on with the broken discredited system? ...
"The Speaker not only presided over the system, he spent a great deal of public money trying to keep the secret secret."
Sir Stuart Bell, backbench member of the House of Commons Commission chaired by Mr Martin, said outside the Commons: "He will not resign, he will not be going anywhere. He will stay as the Speaker of the House representing 646 members."
Sir Stuart conceded: "This matter will not end today, but at the end of the day the Speaker is determined to see it through.
"There will be challenges, there will be threats to his leadership, but at the end of the day he must decide to see us through these diifcult times."
Senior Conservative MP Sir Patrick Cormack said the Speaker should have announced he was stepping down before MPs break up for their summer recess on July 21.
"There is deep disquiet and there is no point in pretending that there isn't," he said. "Therefore I do think this needs to be resolved."
Mr Carswell said two further MPs - Labour's Ian Gibson and Lib Dem Greg Mulholland - had already joined the 15 backing the motion since it was tabled this morning.
He expected more later today and tomorrow, saying: "He has once again shown he is not up to the job."
Mr Carswell added: "Momentum for the motion is growing all the time. More names will come forward today, more will come forward tomorrow."
Labour MP Gordon Prentice said the motion would have to be resolved within days.
"It's inconceivable that a motion of no confidence in the Speaker can lie on the order paper indefinitely," he said. "It has to be debated."
He added: "I don't think Speaker Martin will survive this week. It is our Parliament and our speakership, not his."