A private members' bill, supported by Dean Smith, Trent Zimmerman, Warren Entsch, Trevor Evans and Tim Wilson, has been circulated ahead of a special party room meeting on the issue in Canberra on Monday afternoon.
The legislation would allow two people to marry regardless of their sex or gender.
It also would protect all religious ministers and civil celebrants from legal action if they refuse to marry same-sex couples, and covers service providers - such as bakers, florists and photographers - if they can prove their business is linked to a religious body.
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Senator Smith told the ABC, the move should not be seen as threat to the leadership of the Prime Minister or the government.
"Every difficult issue does not need to be seen through the prism of leadership. This is a test for each and every member of the parliamentary Liberal party first and foremost. It is a respectful place the party room," Mr Smith said.
"People come with their points of view. They do show courtesy to each other. There is an expectation that people come and put their best foot forward and make the most convincing argument that they can. This does not have to be seen through the prism of leadership. I actually think that is a distraction."
Crossbench senator Nick Xenophon, who helped shoot down the plebiscite late last year, said the Smith bill seemed a sensible way forward and he would support it if it got up in the Senate.
Liberal front-bencher Craig Laundy doesn't support the private member's bill.
He says the Turnbull government must stand by its pledge to hold a plebiscite on gay marriage.
Mr Laundy has told the ABC there could be a voter backlash if the government walked away from its election promise to hold a plebiscite on gay marriage.
"I will be when I get into the party room explaining that in the current political environment governments that turn their back on policies they have taken and commitments they have taken to an election, there is a not too distant recent history of that being viewed dimly by those in the electorate."
Gay marriage campaigners have welcomed Senator Smith's private member's bill, calling it strong and robust.
Australian Marriage Equality co-chair Alex Greenwich welcomed the bill as the strongest yet on the issue.
"It's a strong bill. It's a bill which is designed to allow same sex couples access to civil marriage, while respecting the religious protection of marriage. So this is a bill which we hope will gain support, not only from the government partyroom, but indeed from the entire parliament."
The bill outlines the creation of a new category of "religious marriage celebrants" who can refuse to officiate a gay marriage ceremony, without the fear of being taken to court for discrimination.
Director of Legal Advocacy at the Human Rights Law Centre, Anna Brown, says the new category gets the balance between religious freedom and marriage equality.
"Same sex couples will have the dignity and the certainty of knowing when they go to a civil marriage celebrant, they will be not refused service, so this is about protecting civil marriage and not allowing civil discrimination in civil marriage.
"But whilst also protecting religious freedom. So civil marriage will allow same-sex couples and religious marriage will be protected."
Another alternative being considered is a postal vote.
Senator Smith labelled a postal vote an even worse idea.
Marriage equality advocates have promised to launch a High Court challenge if the idea gets up based on legal advice that the government would need specific legislation to hold a postal vote on the issue and allocate sufficient funds.
Rainbow Families spokeswoman Felicity Marlowe believes the postal plebiscite shouldn't proceed.
"For so many Rainbow Families, their children have been waiting a long time to see their mums or dads walk down the aisle and say 'I love you'," she said.
"They know their parents are committed to each other and they know that love makes a family but there's just something about the ceremony and celebration of a marriage that's particularly special. It would be a fantastic day for children in rainbow families when finally they can see their parents married."
