As few as one in three Conservative MPs will support the Marriage (Same Sex Couples) Bill, in next week’s vote, according to Tory MP David Burrowes.
Mr Burrowes, an equal marriage opponent, represents Enfield Southgate in north London.
The Telegraph reports he has surveyed his colleagues’ views and says that up to 200 of the party’s 303 MPs could refuse to vote for the bill.
He claims many Tory MPs were “not satisfied” by the safeguards that have been offered to prevent religious groups being forced to marry gay couples.
Mr Burrowes is a member of the government in his role an aide to the Environment Secretary Owen Paterson, who is also known to oppose marriage equality along with his cabinet colleague Defence Secretary Philip Hammond.
“I’m increasingly confident of the view that there will be well over 100 (against),” Mr Burrowes told the Telegraph.
“I would suggest that the government may struggle to find a hundred Conservative colleagues in favour. The issue for the government will be whether they can get more than a third of the party to vote for them.
“A number genuinely have concerns and want to see those reflected in changes to the bill. Unless they are satisfied, there could be a lot more who will be voting against.”
Earlier this week, Conservative MP Philip Davies, who also opposes equal marriage, told a PinkNews reader that he expects the government’s Marriage (Same Sex Couples) Bill for England and Wales to pass with a Commons majority of between 300-400.