The Conservative party risks losing Christian votes if it goes ahead with legalising gay marriage, a survey conducted by ComRes suggests.

The poll, undertaken on behalf of Premier Christian Media Trust, indicates that more than half of church-going Christians would be less likely to vote Conservative if the government introduces gay marriage rights.

But Revd Colin Coward from the gay rights group Changing Attitudes told Premier’s Sarah Johnston the loss of votes is unlikely to change policy.

83% of those polled were opposed to changing the law, with the most opponents in the older demographics. 90% of over 65s said they were against the plans.

It is estimated that 5 million people in the UK attend a church on a weekly basis.

26% of young Christians aged between 18-34 say they support legalising same sex marriage.

Last week, the Home Office confirmed its decision to allow religious buildings to host civil partnerships. Equalities Minister Lynne Featherstone said regulations should be in place by the end of 2011.

But when plans for a full gay marriage consultation were announced, many religious leaders spoke out against the move.

The Most Rev Peter Smith, the Archbishop of Southwark, welcomed the support for marriage but accused the prime minister of trying to “redefine” the institution.

He told the Daily Telegraph: “Marriage by its very nature is between a man and a woman and it is the essential foundation of family life. The state should uphold this common understanding of marriage rather than attempting to change its meaning.”

The Catholic Bishop of Arundel and Brighton, the Rt Rev Kieran Conry, said the church would “have to do something” to protect marriage.

The Catholic Church, as well as the Church of England, is expected to formally oppose the proposals when a government consultation opens early next year.

The consultation was promised in September after the Conservative Prime Minister’s personal intervention.

ComRes surveyed 544 UK Christians on Cpanel between 25th and 31st October 2011 using an online questionnaire.