Greens MP Adam Bandt has welcomed the growing support for marriage equality expressed by backbenchers today.
A Sky News poll of 39 Labor members conducted today found 22 in support of marriage equality.
"With this motion we set out to create a new level of discussion on marriage equality and we have certainly achieved that goal," Mr Bandt said.
"While our focus has been on the discussion rather than the numbers in Parliament, we are looking forward to a possible vote tomorrow or Thursday."
"Regardless of the outcome, Parliament will have taken a significant step towards acknowledging marriage equality."