In a ComRes poll commissioned by the anti-gay Coalition for Marriage, 23% of Tory supporters said same-sex marriage is a reason not to vote for the party.

The poll offered respondents five reasons why they would not vote Conservative at Thursday’s European elections ranging from policies on Europe to “David Cameron’s determination to legalise gay marriage”.

Just under a quarter (23%) of Tory voters said same-sex marriage is a reason not to vote for the party – however an overwhelming 77% said it would not influence their vote.

Out of all of the 2,000 respondents surveyed, regardless of political party inclination, 28% regarded equal marriage as one of the reasons not to vote Conservative – this was ranked lowest ahead of other reasons.

The highest ranked reason at 56% is the “general dissatisfaction with what the Conservative Party have done recently”.

50% of people who took part in the survey regarded the Conservative’s position on Europe as a reason why they wouldn’t vote for the party.

Colm Howard-Lloyd Chairman of LGBTory, the Conservative Party’s LGBT group said: “While it’s disappointing that just over a quarter of the 2,000 people surveyed cite equal marriage as one of the reasons not to vote Conservative, it’s worth remembering that nearly 7 in 10 Britons believe that same-sex couples should have the right to marry.

“I’m sure when the time comes that voters will react positively to something that is already law, and welcomed by the vast majority.”

According to the poll, 33% of voters aged 65+ regard same-sex marriage as a reason not to vote Conservative, whilst only 24% of voters aged 18-24 have this view.

In April, a poll by Ipsos MORI showed that a majority of Conservative and UKIP supporters are in favour of equal marriage.