A Conservative councillor in Henley has left the Party because of its push to redefine marriage, saying there is no mandate for the move.
And a former local Tory leader has warned that the Prime Minister might face a leadership challenge as a result of the issue, before the next election.
In Henley David Silvester said he opposed several Government policies, but redefining marriage was “the straw that broke the camel’s back”.
In a letter to a local newspaper, Cllr Silvester criticised David Cameron: “His ‘victory’ on a topic that was not in the Conservative election manifesto came by deliberately relying on the wholesale votes of the Labour and Liberal Democrat parties.
“I am not prepared to continue with a local or national party which connives its leader acting in such a way on such an important subject to a Bible-believing Christian.”
Cllr Silvester will now represent UKIP.
It comes as Robert Woollard – a former Wycombe Conservative Association Chairman – has warned about the effect of the same-sex marriage plans.
He said: “If you talk to the people at all levels in society and around the UK, as I have in the last few weeks, they’re saying what is the matter with Mr Cameron, why is he pushing it so far and so fast?
“People are saying they will never vote Conservative again until there’s a change of leadership or the bill is thrown out.”
Asked if he thought Mr Cameron might face a leadership challenge, he said: “I don’t think any challenge will come immediately but I think there could be a challenge before the next election.
“People are more concerned about this than Europe.”
Mr Woollard was among a group of senior local Conservatives who wrote to the Prime Minister with concerns about same-sex marriage earlier this month.
The group said they were concerned about the “growing discord” within the Conservative Party.
They wrote in the letter that if the Marriage (Same Sex Couples) Bill is passed, “Long-held religious and personal freedoms and the right to free speech will be adversely affected”.