The vote on gay marriage has been brought forward from the end of the year and could be held as early as August following concerns from Labor's Right that the debate is damaging the party.

It is accepted on all sides that the push to legalise gay marriage will be defeated.

Protesters march in Melbourne for gay marriage rights. Credit:Craig Sillitoe

According to sources, in this morning's caucus meeting the government whip Joel Fitzgibbon said that due to the desire of some within Labor to "hasten the process", more time would be allotted for the debate, meaning the vote could be held earlier. Because the bill, sponsored by Labor's Stephen Jones, is a private member's bill, there is only limited time for debate on Mondays.

Without extra time allotted, there would have been no final vote until the end of the year at the earliest.