PM outlines $122m gay marriage postal vote

Prime Minister Malcolm Turnbull has confirmed a postal vote will be held on the issue of same-sex marriage if a fresh attempt for a national vote fails again.

Malcolm Turnbull says strong leaders stand by their election promises. (AAP)

Malcolm Turnbull has outlined how Australians will vote on same sex marriage through a $120 million postal ballot if another plebiscite push fails.

A joint coalition partyroom meeting on Tuesday decided to resubmit legislation this week for a national vote and if the Senate rejects it again a voluntary postal vote will be held ahead of a private member's bill following a 'yes' win.

"Strong leaders carry out their promises. Week leaders break them. I'm a strong leader," the prime minister told reporters in Canberra, sticking by the plebiscite policy he took to the 2016 election.