A purely Tory government would not be pressing ahead with reform of the House of Lords in this parliament, Justice Secretary Ken Clarke admitted on Sunday.
The Justice Secretary hinted at tensions within the coalition amid reports that at least six Cabinet ministers would prefer to see the changes delayed.
Philip Hammond, Iain Duncan Smith, Michael Gove, Eric Pickles, Owen Paterson and Lord Strathclyde are said to be among senior Conservatives who have voiced doubts.
The party's backbenchers are also threatening a mass rebellion on the issue, with the potential for resignations by several ministerial aides.
Speaking on Sky News' Murnaghan programme, Mr Clarke stressed that he had always been in favour of an elected upper House.
"The existing House of Lords is a curious historical anomaly," he said. "We are ready for democracy, I think. All three political parties were in favour of House of Lords reform in their last manifestos."
But he went on: "The Liberals probably have determined the timing. I think doing it now in this parliament has happened because the Liberals are anxious to get on with it."
Mr Clarke said there had always been a "minority" in the Commons opposed to an elected Lords, for "various reasons".
But he expressed concern that many Tory MPs were using the policy as a way to attack the alliance with the Lib Dems.
"What I hope is that none of our backbenchers just want to do it because they are against the coalition and the Liberal Democrats, they are suddenly against it because they think it is a Lib Dem thing," he said. "It isn't - it's an all-party thing."
An all-party group of peers and MPs is due to publish a report tomorrow setting out its recommendations for reform.
The Joint Committee is expected to call for an 80% elected chamber, where members serve non-renewable 15-year terms. They would get a salary of around £50,000, rather than the existing attendance allowances.
Deputy Prime Minister Nick Clegg, who is championing the changes, is believed to be ready to give some ground in order to placate opposition.
This could include agreeing to have 450 members in the new House, rather than the 300 he initially favoured. Some 90 of those could be appointed.
The Lib Dem leader could also support allowing peers to hold second jobs outside Parliament.
However, a source close to Mr Clegg told the Sunday Telegraph that he would not permit a referendum on the reforms.
Such concessions are unlikely to come close to satisfying Tories and Labour sceptics.
Writing on his blog, senior Conservative John Redwood warned David Cameron that he was dangerously out of step with his own party.
"I hope the Government is wise, and grasps that this is a topic which needs further discussion and thought," the MP insisted.
"It might be a good idea to seek a consensus first on what the Lords is for, before moving to thinking about how to choose its members.
"Now is not the time to legislate. I have never seen the Conservative Parliamentary party so at variance with its front bench on a single issue."