A Tory MP wants David Cameron ousted as party leader because he “marched us on to the guns” over gay marriage.
Andrew Bridgen, MP for North West Leicestershire, says the issue has driven voters into the arms of UKIP.
He said: “I believe the Prime Minister has blundered by forcing through the gay marriage vote.
“This was something we did not have to do. The PM marched us on to the guns over this and it has cost us a lot of support.”
By pushing ahead with issues like gay marriage, “Mr Cameron has fuelled the rise of UKIP. We have created our own nemesis,” he said.
Mr Bridgen has signed a letter calling for a vote of no confidence in Mr Cameron’s leadership of the Conservative Party.
According to party rules, letters from 46 Tory MPs are needed to trigger a vote, and it is believed as many as 25 have so far done so.
A number of polls show same-sex marriage is a vote loser, the latest coming from a survey by Lord Ashcroft.
At the local elections in May, UKIP surged in support. Election expert, Professor John Curtice, says it won over voters who are socially conservative on issues like gay marriage.
A ComRes poll which accurately predicted the outcome showed that all three main parties would lose votes over the issue.
At the time Colin Hart of the Coalition for Marriage campaign group said the poll was “a real blow” for David Cameron.
Last week, a Tory councillor resigned from the Party because of the Prime Minister’s push to redefine marriage.
Holly Holman quit her membership and stepped down from the Vale of White Horse District Council in Oxfordshire.
Also last week, an ITV News survey showed that three quarters of local Conservative associations had lost members, over half because of gay marriage.
The Marriage (Same Sex Couples) Bill has passed through the Commons and is currently being considered by the Lords.