Australia's ruling coalition is likely to decide whether to allow members to vote on a gay marriage bill according to their conscience.

According to The Sydney Morning Herald, the decision on a conscience vote is likely before the coming spring session of Parliament. A conscience vote is considered critical for passage.

The government has asked Senator David Leyonhjelm to introduce his draft marriage bill.

Leyonhjelm announced the bill last month, saying he would not formally introduce it until Prime Minister Tony Abbott allows members of the ruling Coalition to vote as they choose on the issue.

He said, however, that he will introduce the bill, giving members time to examine the proposal before taking a position.

“I have heard from Liberal senators that a conscience vote is highly likely,” said Leyonhjelm, who represents the Liberal-Democrats.

“If it doesn't get through, I have six years to poke them,” he added. “At some point they will see I am not going to give up on this.”