The majority of Conservative MPs have real doubts about whether David Cameron’s (pictured) plan to legalise same-sex marriage will succeed, according to The Daily Telegraph, and a majority of all MPs say that the law is of little importance to their constituents.

According to an all-party poll of MPs, only 41 per cent of Conservatives believe that the proposal will succeed. Almost as many Tory MPs (37 per cent) feel the proposal will fail and 22 per cent said they were unsure, the survey carried out by ComRes found.

Fifty six per cent of all MPs believe the plan will pass.

It means that three out of five Tory MPs have doubts that the plan will go ahead. By contrast, more than two thirds of Labour MPs and almost all Liberal ­Democrat members polled were confident that it would go ahead.

The poll also found that 60 per cent of MPs did not think that the policy was of “significant importance” to their constituents. Among Tory MPs the proportion rose to 69 per cent.

Coalition ministers have insisted that the question is “how” same-sex marriage could be introduced, not “whether”. 

However opponents claim to have detected a softening of the stance taken by some members of the Government and it has already been made clear that Tory MPs will be given a free vote.

The issue has divided Tory MPs and last week David Cameron appeared ­anxious to shore up relations with religious leaders, insisting that he did not want to “fall out” over the issue. 

David Burrowes, a Conservative MP who has been forthright in his objections to the proposal, said that the strength of opposition in some quarters appeared to have taken ministers by surprise. 

“I think this fairly reflects the fact that there is a significant number of Members of Parliament, particularly Conservative Members of Parliament, who are concerned about whether we should legislate on marriage,” he said.

“That is partly a reflection that there is deep concern from the constituencies.”

More than six out of 10 MPs believed that civil partnerships already provide the same legal rights as would be afforded by marriage.

There was a marked party political divide over this question with only 50 per cent of Labour MPs sharing that view, along with 43 per cent of Liberal Democrats.

The research was commissioned by the Coalition for Marriage, an umbrella group of individuals and organisations that support traditional marriage and oppose plans to redefine it. 

Colin Hart, the group’s campaign director, said: “The results of these polls show that Conservative MPs increasingly think that attempts by the Government to redefine marriage without any electoral mandate are looking uncertain and could well fail.

“Set against the context of growing opposition to the proposals in the country, they suggest that David Cameron is heading for a painful and deeply damaging defeat.”

Meanwhile, a prominent gay MP has suggested that the Government’s move is “pure politics” and that same-sex marriage “isn’t a priority for the gay community” in the UK.

In an interview with the Washington Post, Ben Bradshaw, a former Labour Cabinet minister and one of Britain’s first openly gay members of Parliament said: “We’ve never needed the word ‘marriage,’ and all it’s done now is get a bunch of bishops hot under the collar. We’ve been pragmatic, not making the mistake they have in the U.S., where the gay lobby has banged on about marriage.”