U.S. House of Representatives Speaker John Boehner and Secretary of State John Kerry said on Thursday President Barack Obama would seek congressional authorization for using military force against Islamic State soon and also called for speeding up assistance to Jordan.

"I'm expecting that there will be an authorization for the use of military force sent up here in the coming days. And we're going to go through a rigorous set of hearings and continue to discuss it," Boehner, the top House Republican, told reporters.

Kerry said in Kiev on Thursday that "the president will make his decision, I'm confident, soon," Kerry told journalists after the White House signalled it may be ready to provide weapons, adding that "the first preference is obviously to be able to resolve this through diplomacy."

He added that "it is also going to be incumbent upon the president to go out there and make the case to the American people," as well as help push Congress to pass the authorization.

The United States is leading an international coalition against Islamic State, prominent in Iraq and Syria. Earlier this week the militants drew international condemnation after they posted a video of a captured Jordanian pilot being burnt alive.

"There's an awful lot of things already in the pipeline but speeding that process up through the bureaucracy would certainly help the Jordanians in a time of significant need. And I think, frankly, all of Congress would support it," Boehner said.