David Cameron's call for the introduction of same-sex marriage is out of step with Tory voters, according to a new poll.
Half of the party's supporters are against the move in principle, with just 35% in favour.
However, research by ICM for The Sunday Telegraph found the wider public backed it by a margin of 45% to 36%.
Tensions have been rising over the controversial issue since Britain's most senior Catholic, Cardinal Keith O'Brien, branded the proposal a "grotesque subversion of a universally acknowledged human right".
The Government will launch a consultation next week, with the Prime Minister signalling he wants new laws in place by the 2015 general election. There could be a Bill paving the way for the changes in the Queen's Speech to Parliament in May.
According to the poll, nearly four-fifths of people think it is wrong to fast-track legislation, while only 14% say it is right to do so.
Among Tory supporters, the number against prioritising the change rose to 88%.
Around half of those questioned opposed schools teaching that same-sex marriages were the same as straight ones, compared with a third who thought they should.
Meanwhile, a letter from two senior archbishops will be read in 2,500 parish churches on Sunday morning, arguing that the change would reduce the significance of marriage.
Archbishop Vincent Nichols, the leader of the Catholic Church in England and Wales, and Archbishop Peter Smith, the Archbishop of Southwark, will tell Catholics they have a "duty to do all we can to ensure that the true meaning of marriage is not lost for future generations".
Cabinet Office minister Francis Maude, a leading Tory moderniser, warned last week that the party would be "unelectable" if it stuck to "backwards-looking social attitudes".
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