There are enough supporters of same-sex marriage in Parliament to change the law if Coalition MPs were allowed to vote according to their conscience.
But the political hurdles along the way to changing the law amount to more than just numbers.
Are gay people closer to being able to get married?
Labor, the Greens and some crossbenchers want that vote to happen immediately.
But a vote is unlikely soon because at the last election, the Coalition promised to have a plebiscite — or a national poll first.
The Senate blocked that last November and the Government has not tried again since.
Next Tuesday pro-gay marriage Liberals like Warren Entsch, Dean Smith, Tim Wilson, Trent Zimmerman and Trevor Evans will ask their colleagues to dump the plebiscite and instead have a conscience vote in Parliament.
But Malcolm Turnbull is standing by the plebiscite.
Liberals who say marriage should only be between a man and a woman, including Eric Abetz and Craig Kelly, say abandoning the plebiscite would break an election promise and damage the Government.
Tim Wilson doesn’t accept that — he argues he has “discharged his responsibility” on the plebiscite by voting for it once and it is now time to find another resolution.
What could resolve the deadlock?
There is no sign the Coalition partyroom will agree to a conscience vote. It is more likely to ask the Senate again to support a plebiscite, but the Upper House numbers have not changed, almost certainly making that request futile.
A postal ballot is emerging as another option, where all eligible voters would get a ballot paper mailed to them.
Legal questions have now surfaced about that too with suggestions even a postal ballot would need Senate backing.
That leaves same-sex marriage supporters in the Coalition considering the radical option of joining Labor, Greens and crossbenchers to force a parliamentary vote.
That would involve a parliamentary tactic called “suspending standing orders”, which needs an absolute majority of 76 votes.
It looks to be a possible but risky manoeuvre. Their opponents inside the Coalition have already warned them that would threaten Mr Turnbull’s leadership and the Government’s authority.
What would a postal plebiscite mean?
It would clear the political hurdle the Coalition created in 2015, when it promised to first put the issue to the people.
It might also ease some Coalition tension if it stops that small group of Liberals from following through on the tactic of trying to force a vote.
But it will not prevent the issue dragging on and dominating debate because the two sides of the marriage debate will run passionate public campaigns.
And because the postal ballot would not be binding, it would not resolve the issue.
Some MPs might choose to vote the way their electorate votes — others will be guided by the national outcome of the postal ballot and another group might stick to their existing position either for or against same sex marriage.
The final decision on whether same-sex marriage is legalised would still be decided by a vote of Federal parliamentarians.