The Palmer United Party turned independent Senator commented on fellow Queensland Canberra colleague Wayne Swan's recent admission he was wrong to stand against same-sex marriage and would now support making it legal.

Mr Lazarus told ABC Radio 612 Brisbane he was in favour of the move.

"As I said in the past I think there is way too much child abuse, too much abuse against women - I think if two people love each other, whether they've got penises or they've both got vaginas, they should be allowed to be married," he said.

But he said he didn't believe that politicians should be in charge of the decision.

"What I do agree with, and a lot of people are saying, is why are politicians the ones that have got to decide this?

"I think we should take it to a referendum. Unfortunately a lot of politicians are bound by party policy: we either have a conscience vote, or we get a referendum going and I would guarantee, the majority of Australians would support gay marriage, and if they don't I'll turn up to Parliament House in a mankini."

Mankinis were made famous by comedian Sacha Baron Cohen in his role as Borat.  They have been used as a threat against humanity ever since.

A recent analysis of the federal parliament by Australian Marriage Equality found same-sex marriage was just a handful of votes away from passing, with the lobby group confident 72 lower house MPs would vote in favour of the change, leaving it just four votes shy of the 76 needed.

In the Senate, where Mr Lazarus sits, it believes the vote would pass, by one.