The strong backing for a change in the law comes after the Archbishop of Westminster queried the democratic legitimacy of the coalition plans.
Vincent Nichols, head of the Roman Catholic Church in England and Wales, used his Christmas Day message to attack the “shambolic” process that could soon put same-sex weddings on the statute book.
“There was no announcement in any party manifesto, there’s been no green paper . . . yet here we are on the verge of primary legislation,” Dr Nichols told the BBC.
He also lashed out at David Cameron, accusing him of rushing through legislation for which he had no mandate and which was “a bit of a sham”.
“Basically the prime minister has said, ‘where there is love and commitment, then that’s all that you need for marriage’ . . . but I think that’s very shallow thinking, and it’s a shame that these matters have not been given much, much more thought,” he said.
The plans also came under fire from a high court judge, who said the government should instead be looking at the “crisis of family breakdown”.
Sir Paul Coleridge said too much time had been put into the debate for “0.1 per cent of the population”.
Opinion polls
The ICM poll just before Christmas found 62 per cent of voters support the proposals, with 31 per cent opposed. Most previous polls have found opinion leaning the same way, although the two-to-one margin is particularly emphatic.
An ICM online survey for the Sunday Telegraph in March asked the identical question – which reminds people that civil partnerships already exist for gay couples – and established a 45-36 per cent lead for the reformers.
Mr Cameron’s embrace of gay marriage has proved controversial, not only with religious leaders but also with the Conservative backbench.
However the new poll reveals a significant swing towards the reform; although Labour and Liberal Democrat supporters are more likely to support gay marriage, there is now a majority among Conservative supporters.
Among those who voted Tory in 2010, gay marriage now enjoys 52-42 per cent backing, a big turnaround from ICM’s survey in March, which recorded 50-35 per cent opposition.
Both men and women support gay marriage, although the majority is bigger among female voters, 65 per cent compared with 58 per cent of men.
Age differences
Sharp differences emerge across the age ranges.
The over-65s resist the proposal, by 58-37 per cent, but support is stronger in younger age groups.
The pro-reform majority is 64 per cent among 35-64s, 75 per cent among 25-34s, and an overwhelming 77 per cent among 18-24 year olds.
ICM Research interviewed a random sample of 1,002 adults countrywide in December.
Results were weighted to the profile of all adults.