US Congress is today looking to approve authorisation of use of military force in the war against ISIS.

President Barack Obama has proposed a resolution which limits his own ability to wage war to three years, and rules out ground troops in large concentration.

Peter Baker from the New York Times told Newstalk ZB's Mike Hosking if the Republicans and Democrats can't find a middle ground, it won't actually change anything.

"The president has been waging his war as it is for about six months without any new authorisation of Congress, using old authorisations passed in 2001, 2002. Those are still on the books."

Peter Baker says if Congress doesn't pass anything, Obama can still do whatever he wants to do, based on the old authorisations.

"Because he already still has again the legal power to do what he wants and he's trying to say for this resolution is, 'this is the limits of what we propose to do here and if it's going to change, my successor will make that decision'."

Meanwhile, Tony Abbott has so far denied rumours about a potential deployment of combat troops.

Sky News chief political reporter Kieran Gilbert says the Australian Prime Minister doesn't deny raising or discussing it at some point.

"The Australian newspaper says that the Prime Minister, in the company of his chief of staff, did raise the prospect of 3000-plus troops heading there almost in a unilateral way, in a combat role without coverage of the US or other allies."