Gay marriage is supported amongst voters by a margin of two to one, according to a poll published on Thursday.
Some 62% of those questioned by pollsters ICM Research for The Guardian said that same-sex couples should be allowed to, against 31% who oppose the change and 7% who did not know.
And the poll showed a majority of Conservative supporters in favour of the change, which has been championed by Prime Minister David Cameron in the teeth of significant opposition from Tory backbenchers.
Some 52% of those who voted Tory in 2010 backed gay marriage, against 42% who opposed it. Supporters of Labour and the Liberal Democrat were more likely to approve of equal marriage rights.
The poll shows stronger support for the reform than previous surveys, including an ICM Research poll in March which found 45% in favour and 36% opposed.
The coalition Government is committed to legislating on gay marriage by the 2015 general election, and a Bill is expected to be tabled next month. Cameron has promised his MPs a free vote on the issue.
It has been predicted that half of Tory MPs will vote against but a House of Commons majority should be secured with Labour and Lib Dem help.
It is less clear how the House of Lords will vote.
The results come as Culture Secretary, Maria Miller, signals that the government may use the Parliament Act to force through legislation, the Daily Telegraph reported.
The proposal has sparked stiff opposition from the Church, with the head of Roman Catholics in England and Wales, the Most Reverend Vincent Nichols, Archbishop of Westminster, using his Christmas Day message to denounce the plans as "Orwellian" and "shambolic".
High Court Judge, Sir Paul Coleridge, called the plans "the wrong policy" this week.
He said: "So much energy and time has been put into this debate for 0.1% of the population, when we have a crisis of family breakdown.
"While it is gratifying that marriage in any context is centre stage...but it (gay marriage) is a minority issue."