David Cameron and Nick Clegg could spark a constitutional crisis if they try to force through plans for a new elected Senate, according to a poll.
Some 80% of peers oppose introducing a wholly or mainly elected upper chamber, even though the policy was in the manifestos of all three major parties, a survey for The Times found.
Nearly three-quarters also believe it would be unconstitutional for ministers to use the Parliament Act to push through such proposals.
The coalition partners have pledged to create an elected Lords by 2015, threatening to overcome objections with the rarely-used mechanism that allows MPs to pass legislation without peers' consent.
However, the research highlights hostility to the move across the political spectrum - including among Liberal Democrats.
The newspaper sent questions to each of the 789 peers entitled to sit in the Lords, of whom around 400 do so regularly.
Responses were received from 310, broadly in proportion to their parties' representation in the chamber.
Some 80% opposed a wholly or mainly elected upper House, even though the policy was in all three party manifestos and is in the coalition agreement.
The poll also found 74% believed it would be unconstitutional to use the Parliament Act. And 81% said the Lords works well as it is.
Meanwhile, the poll revealed Mr Clegg's peers are deeply divided, with 64% believing that the Lords works well, 46% opposing a large elected element, and 54% saying it would be unconstitutional to use the Parliament Act.
