A Liberal senator is pressing ahead with a bill to allow same-sex marriage, labelling the government's plebiscite policy "divisive" and aimed at delaying change.
West Australian senator Dean Smith will be among Liberal MPs attending a special partyroom meeting in Canberra on Monday, convened to discuss a way forward on the historic change to marriage laws.
Nationals members meeting in Rockhampton on Friday are expected to recommit to the plebiscite policy, which originated from a joint meeting of the parties in 2015 under Tony Abbott and is understood to be part of the coalition agreement.
Senator Smith said allowing Liberal MPs a free vote in parliament on same-sex marriage was in line with the tradition of Robert Menzies and John Howard.
It also delivered on a key party principle - equality before the law for all people.
"The time is now for a parliamentary vote on same-sex marriage," he told Sky News on Friday.
The public had lost confidence in the idea of a plebiscite, describing it as a "tool for delay."
Liberal colleagues have flagged the idea of a postal vote, which would not require parliament to pass a bill and would be cheaper.
Related reading
Solid majority now favours legalising same-sex marriage
Senator Smith said promoters of the postal vote such as cabinet minister Peter Dutton deserved credit for seeking to find a solution, but there were too many unknowns - including the cost, whether it would disenfranchise younger voters not currently on the electoral roll, and the "very real consideration" of a legal challenge.
He dismissed claims it was a test of Malcolm Turnbull's leadership.
"Malcolm Turnbull will continue to be the leader up until the next election," he said.
"This is not Malcolm Turnbull's test. This is a test of every member of the parliamentary Liberal party."
Senator Smith plans to circulate his bill in the coming week, which he says will reflect the findings of a Senate inquiry.
Mr Turnbull on Thursday said he was standing by the plebiscite, as promised at the 2016 election, and any change of policy was a matter for the joint coalition party room.
One Nation leader Pauline Hanson has urged Mr Turnbull to stand firm.
"Show leadership and be strong about this," she told Nine Network.
Key crossbench senator Derryn Hinch said a second attempt to launch a same-sex marriage plebiscite was doomed to fail.
"If they bring the plebiscite to the Senate again, (Nick) Xenophon and I will knock it down. If they bring a postal plebiscite to the Senate, we'll knock it down. Give them a free vote," Senator Hinch told Sky News.
Senator Xenophon insists his party, which has three senators and a lower house member whose votes would be critical to mounting a plebiscite, remains opposed.
Labor leader Bill Shorten says his party would support a move to suspend business in parliament to bring on a private member's bill.
He does expect a "very small number" of Labor MPs will still vote against same-sex marriage.
