WASHINGTON (Reuters) - A senior Republican senator on Sunday warned U.S. President Donald Trump against pulling U.S. troops from Syria, saying it would lead to a resurgence of Islamic State and increased Iranian sway over the Syrian government in Damascus.

"It’d be the single worst decision the president could make," Republican Senator Lindsey Graham, a member of the Senate Armed Services Committee, said on the Fox News Sunday program.

"We got ISIL on the ropes. You want to let 'em off the ropes, remove American soldiers," Graham said, using an acronym for Islamic State.

With Islamic State having lost almost all the territory it once held in Syria, Trump has told advisers he wants an early exit of U.S. troops.

That position appears to put the president at odds with U.S. military officials, who see the fight against Islamic State as far from complete.

The White House's National Security Council is expected to meet early next week to discuss the U.S.-led campaign against Islamic State in Syria.

A senior administration official told Reuters that Trump's advisers believe the U.S. military needs to stay in Syria in small numbers for at least two more years.

Trump is unhappy with the advice, but it is unclear if he will actually order a troop withdrawal, the official said.

About 2,000 U.S. troops are deployed in Syria.

Graham, in the television interview, echoed White House advisers' concerns about an early pullout.

"This is a disaster in the making," he said.

"There are over 3,000 ISIS fighters still roaming around Syria," Graham said, using another acronym for Islamic State. "If we withdrew our troops anytime soon, ISIS would come back, the war between Turkey and the Kurds would get out of hand, and you’d be giving Damascus to the Iranians without an American presence."

(Reporting by Warren Strobel and Steve Holland Editing by Bill Rigby)