By Patricia Zengerle
WASHINGTON (Reuters) - The White House is expected to ask the U.S. Congress soon for a formal authorization to use military force against Islamic State, a top Republican senator said on Thursday.
Bob Corker, who heads the Senate Foreign Relations Committee, said he has been talking to officials from President Barack Obama's administration and was optimistic they might soon spell out to Congress what they would like to see in an authorization.
"I had a conversation yesterday evening with them about it," Corker told reporters at the U.S. Capitol.
"They need to let us know the type of authorization they are seeking, and I think that that may happen in the near future, the very near future," the Tennessee Republican said, declining to give a more specific time frame.
The White House had no immediate comment.
The Obama administration has argued that its five-month-long campaign of air strikes in Iraq and Syria against Islamic State militants is legal, based on authorization passed in the early 2000s under President George W. Bush for the Iraq War and fighting al Qaeda and associated groups.
But several members of Congress have said it would be preferable to debate and pass a new authorization for combating Islamic State fighters, who have killed thousands of people while seizing swaths of territory in Iraq and Syria.
Obama said at a news conference in November, just after sweeping election victories gave Republicans control of both houses of Congress, that he would seek fresh authorization from lawmakers so the world knows Washington is "united behind this effort."
Earlier on Thursday, U.S. House of Representatives Speaker John Boehner called on Obama to send Congress the administration's plan for using military force against Islamic State soon and said his fellow Republicans would work with the White House to pass it.
(Additional reporting by Roberta Rampton; Editing by Grant McCool and Leslie Adler)