Labor and the Greens have played tit-for-tat politics to prevent the Senate from voting on same-sex marriage.
Hours after the Greens helped thwart an attempt to bring on a vote of their own private bill, Labor sided with the coalition to stymie a similar move by the minor party.
"If we ring the bells now we can be hearing wedding bells in no time," Greens senator Janet Rice told the Senate on Thursday.
Yet earlier, the Greens voted with the coalition against a move by Liberal Democrat David Leyonhjelm to bring on a vote of their bill.
That move would have delayed a debate - already expected to go through the night - on legislation that changes the way Australians vote for the Senate.
Labor slammed the Greens for twice in three days blocking a Senate vote on same-sex marriage.
Opposition Senate leader Penny Wong launched a scathing attack on the minor party, accusing the Greens of caring more about eliminating minor parties than eliminating discrimination against same-sex couples.
"Don't you ever come in here and tell us how committed you are to this issue," she told parliament on Thursday.
Greens senator Rob Simms accused Labor of using same-sex marriage as a "cheap political wedge".
"Please stop using this issue in such a cheap and cynical way, it's actually people's lives you're stuffing around with here," he told parliament.
It was a "complete and utter lie" to suggest the Greens had voted against same-sex marriage.
Senator Wong, who has two children with her female partner, was unimpressed, saying she did not need to be lectured about an issue impacting people's lives.
