Conservative MP Glyn Davies says he is disappointed that the prime minister, deputy prime minister and chancellor are all supporting equal marriage.
Writing on his blog, the Montgomeryshire MP confirmed that he would be voting against the measure and has also criticised George Osborne for going “big” on same-sex marriage in a newspaper article on Tuesday.
Mr Davies said: “The reason I’ve not chosen to speak on the matter is that I will be accused of being homophobic – which is just not true. If this proposal was going to confer some new right upon gay people I would probably support it.
“But it doesn’t. It just redefines a word which has great meaning for hundreds of thousands of good people across Britain – for no real purpose, other than to convey some ill-defined ‘message’”.
Mr Davies says he was recently asked for his thoughts on the subject during the paper review on the BBC News Channel.
In his blog post, he also made a reference to yesterday’s criticism of the prime minister by the chief executive of ComRes Andrew Hawkins.
Mr Davies says he intends to raise the matter with the prime minister, saying: “I need to have a chat with my old boss about this next week!”
Meanwhile, a Conservative Party spokesman said Downing Street would respond to Mr Hawkins’ letter “in due course”.