Faith schools should be required to have anti-homophobic bullying policies in place, Lib Dem leader Nick Clegg has said.
Gay couples should also be given the symbolic right to describe themselves as "married" rather than civil partners, he said.
Mr Clegg made a pitch for the so-called 'pink vote' as the parties continue to manoeuvre ahead of a general election that is expected to take place in May.
He said faith schools must ensure they do not become "asylums of insular religious identity".
"If they're suffering higher rates of homophobic bullying and violence then we need to put serious pressure on them. It needs to be a requirement; it just needs to be a requirement across the piece," he said.
Mr Clegg launched a scathing attack on David Cameron's record on gay rights, describing the Tory leader as "very difficult to trust" on the issue.
He pointed out that Mr Cameron had originally voted against the repeal of Section 28 - which banned local authorities and schools from "promoting" homosexuality - although he has since recanted.
The comments come after Mr Cameron made a bid to woo Lib Dem voters in his New Year message, insisting the difference between the parties was less than before.
"He's a confection," said Mr Clegg. "I don't really know what he believes in. I don't know what his convictions are and the reason is because they keep changing - and they seem to change for convenience. So when it mattered, when people went through the lobby to vote on Section 28, his convictions were on the wrong side. Suddenly they've changed and we get an apology!"
In an interview with Attitude magazine, reproduced in the Independent, the Lib Dem leader praised Labour's record of introducing civil partnerships and equalising the age of consent. But he said more had to be done, pledging reforms including reversing the ban on gay men being allowed to give blood.
