It is “highly likely” that MPs from Australia’s governing Liberal party will be allowed a free vote on an upcoming same-sex marriage bill for the first time.

According to lone Liberal Democrat MP David Leyonhjelm, who first announced he would introduced a same-sex marriage bill last month, it is “highly likely” the government will allow MPs a free vote on the issue.

Senator Leyonhjelm told the Sydney Morning Herald that he has sped up the process, while he previously only planned to introduce the bill after a conscience vote was secured.

He said: “I have heard from Liberal senators that a conscience vote is highly likely.”

Despite 72% of Australians supporting marriage equality, with just 21% opposed, Liberal Prime Minister Tony Abbott remains staunchly opposed.

However, one Liberal MP told the newspaper: “I don’t think even Tony Abbott will stand up in the party room and argue against a conscience vote. It would appear to go against Liberal principles. I don’t think you would find any of my colleagues who would say a conscience vote was a bad idea.”

Leyonhjelm, who is newly-elected, added: “If it doesn’t get through I have six years to poke them. At some point they will see I am not going to give up on this.”

The last vote on same-sex marriage in Australia was held in 2012, when the House of Representatives rejected it by 98-42, and the senate by 41-26.