The influential political commentator Tim Montgomerie has become the latest high profile Conservative figure to record a 'Out4Marriage' video in support of gay marriage.
The editor of the grass-roots Conservative Home website surprised many when he expressed his support for David Cameron's plans in February.
Writing on ConHome he said: "It is because I value marriage so much that I have come to believe it should be extended to gay people and not kept exclusive.
"Because it is so beneficial an institution it should be enlarged rather than fossilised. Whereas some people see the gay marriage issue as primarily about equal rights, I see it as about social solidarity and stability."
In the video published over the weekend he says: "For me marriage s one of the most important Conservative institutions, it binds people together almost like no other institution that man has ever created.
"It's an institution that builds the best in society its a compassionate, caring, inclusive institution and I want as many people as possible to feel part of it.
He adds: "That is why I am 'out4marriage', 'out4marriage' for gay people as well as for straight people."
Montgomerie's view is at odds with many Tory MPs and some minister's who do not want to see the law changed to allow gay people to marry.
Downing Street has said it will allow Conservative MPs a free vote on the issue in order to let them vote against the plans without formally being forced to oppose the government.
By contrast Nick Clegg has said all Liberal Democrat MPs will be expected to vote in favour of the plans as is government policy.
Several prominent politicians have also recorded videos expressing their support for gay marriage including home secretary Theresa May:Suggest a correction