After hundreds of hours of debate, same-sex marriage looks set to pass the Parliament today, meaning it could be just days before it is legal.

More than 100 MPs have delivered speeches on the issue this week and most support a change to the definition of marriage.

The Senate has already passed the bill without amendments and the House of Representatives is expected to do the same later today.

The Governor-General could ratify the law this week to make same-sex marriage legal, which would meet Prime Minister Malcolm Turnbull's hope to get it done by Christmas.

On Wednesday night, Government MP Sarah Henderson gave an emotional speech and said it "means very much to my own family, this change in the law".

Loading

She paid tribute to a "very dear friend", John Parker, who died "very tragically a number of months ago".

"I don't want to say too much about John because he was gay and it was something he had a lot of struggles [with]," Ms Henderson told the Parliament.

"He really wanted to see this change in the law … I'm sorry I'm crying.

"In one of the last conversations I had with him he just said to me 'Hendo, just bloody well get on with it ok?'.

"And I say to JP, my dear, beloved friend who I miss so dearly: JP, that's what we are doing."

Labor frontbencher Chris Bowen said it had been a long wait for same-sex couples who want to marry in Australia.

"It's time that that occur and I'm proud that it will occur," Mr Bowen said.

The first legal same-sex weddings in Australia could happen about January 8, 2018.