New Archbishop of Canterbury challenges David Cameron on gay marriage A group of 20 Tory constituency chairmen delivered a letter of protest to Downing Street warning the Prime Minister that the reform could cause "significant damage" to Tory election chances in 2015. Up to 200 of the 303 Tory MPs are expected to rebel or abstain during the vote, leaving Mr Cameron reliant on Labour and Liberal Democrat MPs to pass the measure. Both Anglican and Catholic leaders made last-ditch efforts to persuade MPs to vote against the same-sex marriage Bill. The Archbishop of Southwark, the Most Rev Peter Smith, told parishioners during a mass that the Bill is "ridiculous." He urged them to pray for its defeat and to lobby their MPs. Archbishop Smith, who is the second most senior Catholic cleric in England and Wales, told The Telegraph: "The definition of marriage as a union of one man and one woman pre-dates both the state and the church and as such neither has the right to change it. The complementarity of the marital relationship is hard-wired into human nature. The Most Reverend Bernard Longley, the catholic Archbishop of Birmingham, urged all MPs who were "uncertain, wavering or planning to abstain" to gather their "courage" and vote against the "ill-conceived Bill." "This Bill is being rushed through Parliament by the Prime Minister without a mandate and without proper consultation," he said. The Church of England has written an eight-page briefing note on the Bill to every MP ahead of the vote. It warns that the legislation has been prepared in "great haste" and will have a "chilling effect" on teachers and public officials who express the view that marriage should be between a man and a woman. "We doubt the ability of the Government to make the legislation watertight against challenge in the European courts or against a 'chilling effect" in public discourse," it says. We retain serious doubts about whether the proffered legal protection for churches and faiths from discrimination claims would prove durable. Too much emphasis, we believe, is being placed on the personal assurances of ministers. The Conservative rebels who wrote to Downing Street are calling for the Bill to be delayed until after the next election in 2015 to allow the party and the public "more time" to debate such a radical social change. "As long-standing members of the Conservative Party we want to support the party to victory, as we have done in every past election," they wrote. Resignations from the party are beginning to multiply and we fear that, if enacted, this Bill will lead to significant damage to the Conservative Party in the run up to the 2015 election. Ed Costelloe, who resigned as chairman of Somerton and Frome Conservative Association over the gay marriage proposals last month, said grassroots Tories were "shocked" by the way the reforms were being rushed through Parliament. "We worked hard locally to convince people to support Conservatives but this was not part of the platform," he said. Tim Loughton, the former children's minister, expressed fears that teachers and faith groups would be forced in the European Court to accept gay marriage "against their will." The Government's proposed "quadruple lock" of legal protections for the Church of England was "nonsense" that would not "hold up" in courts, Mr Loughton told Sky News. However, Ed Vaizey, the culture minister, insisted that the discussions over the policy remained "good natured." "I've got a view, some of my constituents have a different view, some of my fellow MPs have a different view, but I don't think it's tearing the Tory party apart," Mr Vaizey said. A Downing Street source said there was "no pressure" on Tory MPs to support the Bill and that there would be "no consequences" for those who voted against the reforms. "Obviously, the Prime Minister is a strong advocate of it and that hasn't changed," the source said. The Prime Minister is "always open" to talking to colleagues but would not be actively seeking to win over critics.