Opposition Leader Tony Abbott should allow coalition MPs to exercise their democratic right in a vote on same sex marriage, an activist says.
Parents and Friends of Lesbians and Gays (PFLAG) spokeswoman Shelley Argent says legalising gay marriage should be Mr Abbott's priority.
"It is time my son and Tony Abbott's sister were shown the respect they deserve and have their relationships properly recognised," Ms Argent told AAP.
"Marriage equality will cost the country nothing.
"If he (Mr Abbott) was going to be a half-decent leader he would be saying right now that he will allow a conscience vote.
"MPs should be given their democratic right to vote on it."
Ms Argent was confident gay marriage would legalised under a conscience vote.
"I think it would pass - it is surprising how many coalition MPs are in favour," she said.
In Sunday night's leaders' debate, Prime Minister Kevin Rudd pledged to introduce gay marriage legislation within 100 days if returned to government.
But Mr Abbott said there were other, more important, issues to focus on.
