A group of senior local Conservatives has written to the Prime Minister urging him to delay a vote on gay marriage until after the next election.
MPs are preparing to debate and vote on the controversial Marriage (Same Sex Couples) Bill for the first time tomorrow.
The letter, written by 23 former or current constituency chairmen, says the plans have not been talked through.
It reads: “We feel very strongly that the decision to bring this Bill before Parliament has been made without adequate debate or consultation with either the membership of the Conservative Party or with the country at large.”
The group says they are concerned about the “growing discord” within the Conservative Party.
They wrote in the letter that if the Bill is passed, “Long-held religious and personal freedoms and the right to free speech will be adversely affected”.
Edmund Costelloe, who recently resigned as chairman of Somerton and Frome Conservative Association over the gay marriage proposals, said: “Many of us feel a huge sense of personal betrayal over these plans.”
Mr Costelloe said: “We are also shocked by the way in which it is being pushed through with so little regard for proper scrutiny.”
He added: “There is huge public concern at the local level and we are seeing people leave the Party. It is certainly not a vote winner.”
The letter was handed over personally to Downing Street by a delegation of six senior grassroots Conservatives at the weekend.
Peter Steveney, of the Thirsk and Malton Conservative Association, said his main concern is “that it’s so completely unnecessary to do this”.
He added: “We are losing members. The timing is so bad. This could have devastating effects.”
Last year, a poll showed that more than seven out of ten Conservative constituency chairmen think redefining marriage should be scrapped.