Former UK defence secretary Dr Liam Fox says gay marriage is not a priority, comparing it to 'social engineering'.
The Conservative MP told Sky News that the government should concentrate on fixing the economy instead of issues which only effect the 'metropolitan elite'.
His comments come just days before a public consultation on legalizing same-sex marriage in England and Wales closes.
'This is a contentious issue but I have to say that I am much more in favour of social mobility than social engineering,' Dr Fox said.
'I think that the vast majority of the public have a completely different set of priorities from what I would call the metropolitan elite and I think they will be looking for economic and social issues to be dealt with first.'
Dr Fox has joined other members of his party to oppose the coalition government's plans, including Northern Ireland secretary Owen Paterson and defence minister Gerald Howarth, despite support from Prime Minister David Cameron and Home Secretary Theresa May.
The proposal has also been slammed by high profile religious leaders from the Catholic and Anglican churches, including Archbishop of York John Sentamu.
A ComRes poll last week showed the majority of gay people supported same-sex marriage, with 77% believing marriage should not be exclusively for straight couples.
The UK government's consultation on legalizing gay marriage in England and Wales ends on 14 June.
Campaigners are urging people to complete the short official survey as a large anti-gay religious lobby has dominated submissions so far.
A separate consultation has already been run by the Scottish government, which has also committed to marriage equality and results will be published next month.