Lib MP tips marriage debate in party room

Federal MP Wyatt Roy anticipates a discussion in the Liberal Party room on gay marriage by the year's end.

A Liberal backbencher anticipates a debate in the Party room on gay marriage by the year's end. (AAP)

A Liberal backbencher says he expects same-sex marriage to be debated in the Liberal Party room by the end of the year.

Prime Minister Tony Abbott is facing pressure to allow a free vote among Liberal MPs and senators when a private member's bill allowing gay marriage comes to the parliament.

"I would expect that before the end of the year ... this (same-sex marriage) would come up in the Liberal Party room," Queensland-based coalition MP Wyatt Roy told ABC Radio in Brisbane.