Mr Cameron said peers who 'behave badly' should face tougher sanctions
Conservative leader David Cameron has said his party would change the law to allow peers who "behave badly" to be expelled from the House of Lords.
He told the BBC it was "completely wrong" those who broke the ethics code could not be suspended or expelled.
Earlier Lib Dem leader Nick Clegg said peers who broke the law and faced a jail term should be expelled.
Lords leader Lady Royall has told the Guardian she would back permanent expulsions in "extreme cases".
Four Labour peers have been accused by the Sunday Times of being ready to accept payments of up to £120,000 to help amend laws. They all deny any wrongdoing.
But many peers feel the allegations alone have been enough to do serious damage to the reputation of the House of Lords, where the strongest punishments for wrongdoing is being named and shamed.
Mr Cameron told the BBC: "What is completely wrong is that members of the House of Lords can behave badly, can break every code of ethics in the book and yet they cannot be suspended or expelled from that House of Parliament. So we would change the law."
He added there had to be a clear code of conduct, a committee to investigate complaints and sanctions so "it actually hurts - it hits people in the wallet and means they can't take part in politics."
Mr Clegg called for expulsions to be allowed in extreme cases.
He said current sanctions were "weak", adding: "This case exposes the extraordinary protection enjoyed by the political class: one rule for lawmakers and another for everyone else."
Labour peer Lady Royall, the leader of the House of Lords, has said she believes tougher sanctions are needed.
In an article for the Guardian newspaper, she said there was a need for change in the rules, including on consultancy work, and tougher sanctions against those who broke them.
She said she would recommend a range of sanctions including the immediate suspension of peers who are under investigation, longer suspensions if cases are proven and the possibility of "permanent exclusions in extreme cases".
But she said as peers were not paid a salary, they had a right to earn a living, otherwise the House of Lords would be full of only the wealthiest people.
Four Labour peers were accused by the Sunday Times of being prepared to take up to £120,000 to help amend legislation.
They are former energy minister Lord Truscott; former defence minister Lord Moonie; Lord Taylor of Blackburn; and former Labour whip Lord Snape - all of whom deny any wrongdoing.
In her article, Lady Royall said she had spoken to all four, who "insisted vigorously" they had done nothing wrong and "genuinely believe that".
Two Lords inquiries have begun, one looking at the claims and another looking at sanctions that can be taken against peers.
Lady Royall added they would be "thorough and rigorous", adding: "A new complaints procedure we adopted recently will ensure that those involved will get a fair hearing. We will not have trial by media."
The Lib Dems have urged police to investigate the allegations and received a letter from the Metropolitan Police, saying it is "being considered" by the Specialist Crime Directorate.