Nick Clegg, the Liberal Democrat leader, says he wants a change in the law to allow gay couples to have a civil marriage.
Mr Clegg, responding to a direct question on changing the law, said he supported gay marriage because: “Love is the same, straight or gay, so the civil institution should be the same, too.”
“All couples should be able to make that commitment to one another”, he said.
Mr Clegg was responding to questions from readers of the gay news website pinknews.co.uk.
In a wide-ranging interview the Lib Dem leader also acknowledged the importance of free speech laws which allow Christian street preachers to say “homosexuality is a sin”.
Mr Clegg stated: “I’m afraid I believe freedom of speech is vital in a free society like ours.
“Too much has already been taken away, and we would protect it.”
But he also said: “Homosexuality is normal, and I wish everyone accepted that.”
He declared that schools, including faith schools, should have policies in place which say that homosexuality is normal and harmless.
He also said teachers “should explain that whenever appropriate”.
Mr Clegg reiterated his call for an end to the safeguard in the blood transfusion system which means men who have had sex with other men cannot give blood.
He said: “The NHS is always in need of blood, so a blanket exclusion is just daft.”
The party leader added: “The NHS should review this and work out appropriate rules so that gay men can give blood safely if they want to.”
But the National Blood Service has previously warned that overturning the current ban on donations would “result in a fivefold increase in the risk of HIV-infected blood entering the blood supply”.
Mr Clegg was criticised for comments he made in a gay lifestyle magazine earlier this year in which he said that faith schools should be forced to teach that homosexuality is normal and harmless.
Following his comments a spokesman for the Church of England said: “Whatever one’s view on sexual ethics, the notion people should be forced to teach as fact what are arguably matters of belief is disturbing.”
And Norman Wells, Director of the Family Education Trust, said “Not only is Nick Clegg showing a woeful lack of respect for faith schools, but he is also totally disregarding the deeply-held views of parents.”