Nearly a third of David Cameron's shadow cabinet voted against gay rights legislation at some point over the last two parliaments, demonstrating their "shameful" record in tackling discrimination, according to the Liberal Democrats.

They have compiled research on four examples of legislation where many Tories voted against equal rights laws. Chris Huhne, the Lib Dem home affairs spokesman, said progress on gay rights would "grind to a halt" if the Conservatives won the election. "The Tory record on supporting gay rights is nothing short of shameful," he said. The Lib Dem research shows:

• Ten out of 32 members of the shadow cabinet voted against at least one piece of gay rights legislation. The shadow Europe minister, Mark Francois, voted against all four.

• David Cameron, Kenneth Clarke, Mark Francois, Chris Grayling, William Hague, Francis Maude, Patrick McLoughlin, Andrew Mitchell, George Osborne and Sir George Young voted against legislation to repeal section 28, which had banned local authorities and schools from "promoting" homosexuality, in 2003.

• Nineteen members of the shadow cabinet joined the attempt to block the equality bill, which included a requirement for all publicly funded bodies to promote equality.

• Seven members of the shadow cabinet voted to allow only heterosexual married couples to adopt in 2002.

• Four of the shadow cabinet voted against powers which passed through the house in March 2007 giving the secretary of state the ability to bring in regulations with a new definition of discrimination and harassment on grounds of sexual orientation.

• Thirty-five Tory MPs voted to allow only heterosexual married couples to adopt in 2002 and a third also voted against the Equality Act (Sexual Orientation) Regulations in March 2007, allowing the government to make regulations defining discrimination and harassment on grounds of sexual orientation.

This week Nick Clegg has made a claim for some of the UK's sizeable "pink vote" with an interview in Attitude magazine. The Lib Dem leader is working hard to distinguish himself from the Conservatives after Cameron used his new year message to appeal to Lib Dems and claim he has turned the Tory party into the natural home for "liberal Conservatives".

Clegg proposed a series of measures including reversing the ban on gay men being allowed to give blood; a requirement that faith schools implement "anti-homophobia bullying policies" and teach that homosexuality is "normal and harmless"; a change in the law to allow civil partnerships to be regarded as marriage; and a guarantee of asylum to refugees who have fled a country because of persecution over their sexual orientation.