The political arguments on whether equal marriage is a vote winning policy for the Conservative Party shows no sign of dying down, as ComRes releases another poll.

According to the Daily Mail, in a ComRes survey of more than 2,000 people, one in four voters says the issue could sway their vote at the next general election. But while 7% say they are more likely to vote Tory, 18% – more than twice as many – say they are less likely to.

More significantly, the effect is dramatically magnified among those who voted Conservative in 2010, but say they may not do so at the next election.

Only 4% of this group say they are more likely to vote Tory because of equal marriage, while 34% say they are less likely to.

The poll also revealed that 62% of those surveyed were against “redefining” marriage.

Only 23% thought that Chancellor George Osborne was correct to argue that legalising same-sex marriage would help the Tories win the next general election.

68% of Tory voters believe marriage should continue to be defined as a “life-long exclusive commitment between a man and a woman”.

In response to the survey, Colin Hart, the campaign director of the anti-gay Coalition for Marriage, said: “This poll is the latest blow to a profoundly undemocratic plan that day by day is falling apart before our eyes.

“It is unpopular with voters who have never been able to cast a vote on the issue and is costing the Conservative Party votes. As Andrew Hawkins head of ComRes says, this policy could cost the Tories millions votes and scores of seats at the next general election.

Mr Hart added: “Given the weight of polling data on this issue, the biggest government consultation in recent years and a 600,000 strong petition opposing the redefinition of marriage, it is astonishing that the PM’s right hand man, Chancellor George Osborne has tried to put this policy at the heart of the Tory’s election strategy.”

Earlier this month, Mr Hawkins wrote to the prime minister and accused him of misinterpreting a previous ComRes poll on equal marriage, he said the PM had quoted “the wrong figures” and had ignored “the general detrimental impact on the party’s fortunes” of the policy.