Proposals for new powers to "recall" MPs who misbehave could be abused for party political advantage in the House of Commons, the chair of a Westminster standards watchdog warned today.
Labour MP Kevin Barron, who chairs the Commons Standards and Privileges Committee, said he had "grave concerns" over plans to allow a recall vote if MPs are found guilty of "serious wrongdoing".
Parliament would "implode" if members could be forced to face a by-election for no more than breaching their code of conduct, he said.
At present, MPs can be expelled from Parliament only if they are jailed for more than 12 months. Less serious wrongdoing is punished by suspension from the House for a number of days, on the recommendation of the Standards and Privileges Committee.
Government proposals published last month would give voters the power to force a by-election by collecting the signatures of 10% of the electorate in an MP's constituency.
But a recall petition could only be held if the MP has been jailed for less than a year or if the Commons agreed that he or she was guilty of serious wrongdoing.
In practice, that would mean MPs voting on a recommendation from Mr Barron's committee following an investigation by Parliamentary Standards Commissioner John Lyon.
But Barron warned this would put MPs in a position where they were potentially able to end the careers of political rivals for misdemeanours which did not even merit a criminal charge. And if the political balance in the Commons was on a knife-edge, a recall decision could cost the government its majority.
He told the Commons Political and Constitutional Reform Committee, which is carrying out an inquiry into the proposals: "In this parliament, it's not going to matter if one seat goes one way or the other. But look at the Wilson parliament in the 1970s, when sometimes there wasn't a majority in the House or for quite a while a majority of one or two.
"The implications (are) major for the floor of the House. Even if the committee that had to set the bar tried to do it in a non-party political way, what would happen when it went to the floor of the House to be accepted if there were circumstances like that?"
Mr Barron said he was not opposed to granting voters the power to recall MPs, but insisted that the criteria for triggering a petition must be absolutely clear to all concerned.
"I can't see a more transparent system than what we currently have and I would hate to think that that would be disturbed by something that really isn't as clear in terms of where the bar is set," he said.
Any attempt to remove an MP who had not been charged with a criminal offence would inevitably lead to questions over whether it was "proportionate or fair".
Equally, public confidence would be undermined if recall powers were created but never used, because MPs were reluctant to approve the launch of a petition.
"It is essential in my view, if we are being asked to set this bar of 'serious wrongdoing', that everybody - not just Members of Parliament, but the public too - understands exactly what it means," he said.
"If it becomes 'a serious breach of the Code', I have great fears that the Committee and potentially Parliament would implode on that basis."