David Cameron faces losing hundreds of council seats this week because of his plans to redefine marriage, according to a new poll of voters entitled to vote in this week's local elections.

The ComRes survey, carried out ahead of the local elections, reveals that one in four of those who helped put Mr Cameron in Downing Street say the policy is turning them off from voting Conservative.

When asked "does the coalition government's plans to legalise same-sex marriage make you more or less likely to vote for each of these parties in next week's local elections?" a quarter, (26 per cent) of Conservative 2010 voters say less likely, with fewer than one in 10 (nine per cent) saying they were more likely.

Worryingly for Mr Cameron, the poll found evidence that the policy was driving voters into the arms of the UK Independence Party (UKIP), who have seen their poll rating surge in recent months.

More than one in five voters (22 per cent) said they were planning to vote for Nigel Farage's Party which opposes gay marriage. Among Conservative voters in 2010, this rises to one in four (25 per cent) who say they will be voting UKIP today (Thursday). 

On Tuesday, a protest outside the Witney Conservatives constituency office saw former chairman of Chipping Norton Conservatives, Cicely Maunder, hand in a giant postcard signed by hundreds of local people asking Mr Cameron to leave marriage alone.

Don Horrocks, head of public affairs at the Evangelical Alliance, who was at the protest, said: "It was something of a surprise how local people felt so incensed that they were prepared to turn out in their hundreds to tell David Cameron that his policy of playing politics with marriage was a betrayal of their support, including those who had run local Conservative associations for years."

Colin Hart, campaign director for the Coalition for Marriage, said: "The prime minister has consistently backed the proposed changes to redefine marriage as part of the so-called decontamination strategy, but it has not worked. Every section of the electorate are highly sceptical about his motives, believing he is pushing this policy in a cynical attempt to make his party look trendy and progressive."

The poll also showed that twice as many of those who had voted Liberal Democrat in 2010 said that gay marriage is making them less likely to vote for their party compared with more likely, (18 per cent and nine per cent respectively). And one in five Liberal Democrat 2010 voters say they intend to vote Labour.

This week the Northern Ireland Assembly firmly rejected a proposal to rewrite the current definition of marriage by 11 votes, an increased majority from when the assembly last voted on the issue.

This week the One People Commission of the Evangelical Alliance has written to the Daily Telegraph expressing their concerns. On behalf of the ethnically-diverse churches they represent, the leaders have together identified the failure of the government to defend marriage and even to understand what marriage actually is.

The letter states: "The people of the UK need to have their say. These plans were not in any party's manifesto and if the government had any respect for democracy they would allow a referendum before making fundamental changes to the nature of marriage."

As local elections take place across the country this week, how will you be voting? Tell us in our poll of the week.