Terrified Tories have launched a last-ditch bid to put their leaders' equal marriage Bill on ice.
MPs will debate the Bill on Tuesday, which would grant same-sex couples the right to marry as well as to form a civil partnership and allows people to legally change their gender without having to divorce.
The Bill is ostensibly a free vote, but Cabinet ministers, junior ministers and whips are among 180 MPs expected to "rebel" against the PM's plans.
Environment Secretary Owen Paterson, Welsh Secretary David Jones, Defence Secretary Philip Hammond and Work and Pensions Secretary Iain Duncan Smith will either oppose or abstain from voting, along with junior ministers Mike Penning, John Hayes and Jeremy Wright.
Meanwhile party officials delivered a letter from more than two dozen local Conservative associations' chairs to Downing Street, warning of "significant damage" in polls.
And former children's minister Tim Loughton said the Bill was a distraction.
"There's quite a lot of things that were in our manifesto which made it to the coalition agreement which we have yet to deliver, and yet gay marriage is something which we had no green paper, no white paper, no manifesto commitment of any party, it wasn't in the coalition agreement, and all of a sudden it is taking huge priority, it is going to take up a lot of parliamentary time and is going set MP against MP, and we don't need it."
Uncontested legislation before Parliament includes a Bill to allow street traders in the City of London, a Bill allowing female heirs to the throne and a Bill to "appeal against unduly lenient sentences."
Over the border, conservative religious group Scotland for Marriage insists Holyrood's own consultation on a same-sex marriage Bill represents "the destruction of the concept in law of mother and father."
But the Equality Network's Tom French said legislation could only increase religious freedom by allowing faith groups to choose whether or not to extend the ceremony.
"This legislation will increase religious freedom, and that is why most MSPs and many religious people support it," he said.
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