CROYDON South MP Richard Ottaway says he is undecided on the gay marriage debate that is dividing his party.
The Conservative outlined his thoughts to the Advertiser, amid a growing backlash among Tories against David Cameron's plans to legalise gay marriage.
On Tuesday the Government outlined plans which would make the ceremonies legal.
But it said ceremonies would be banned from taking place in Church of England churches.
Mr Ottaway said: "I've not yet reached a conclusion.
"I want to study the Government's proposals in depth and then I will make my position clear."
But he added he agreed with a guarantee offered by the Government that churches and other religious organisations would not be forced to conduct same-sex marriages.
Mr Ottaway, an MP since 1992, added he had received "about 200 e-mails and letters" from constituents on the subject.
He said: "Most of them are not in favour of gay marriage on religious grounds. However, many are identical letters – implying a degree of coordinated lobbying."
About 100 Conservative MPs are thought to oppose legalising gay marriage, while in Shrewsbury, MP Daniel Kawczynski said he would hold a public meeting to help decide his vote, after receiving hundreds of letters from constituents.
Asked whether he would consider doing the same, Mr Ottaway said: "I'm not minded to hold a public meeting."
Croydon Central MP Gavin Barwell has stated his support for gay marriage alongside religious freedom protections.
On December 8, he and 18 other leading Conservatives launched the Freedom to Marry campaign group.
Mr Barwell explained his views in a lengthy post on his website, published on December 9.
He wrote: "I have thought long and hard about this issue and taken the time to listen to the concerns of those who are opposed.
"I am voting for it, provided there is protection for religious freedom, because I think it is the right thing to do.
He added: "Society benefits from people forming stable, mutually supporting relationships even if those involved don't have children – they are likely to be happier and they are less likely to need help from the state if they lose their job or get sick.
"If marriage is such a good thing, why wouldn't we want to extend it to same sex couples?"