Two bills to legalise gay marriage are expected to be introduced to federal parliament on Monday.
Labor backbencher Stephen Jones vowed to introduce a private member's bill at last December's ALP national conference, when his party's platform was changed to support gay marriage but hold a conscience vote in parliament.
Tasmanian independent MP Andrew Wilkie and Australian Greens MP Adam Bandt will also introduce a separate private member's bill on gay marriage.
Mr Bandt fears Labor and the opposition are working behind the scenes to have Mr Jones' bill watered down to civil unions.
Mr Jones told ABC radio on Monday that assertion "was putting the cart before the horse".
A Senate inquiry is set to investigate another gay marriage bill introduced in the upper house last year.
