WASHINGTON — Senators from both parties agreed on Tuesday that it was long past time for Congress to enact a new law authorizing the evolving war against Islamist terrorist groups, while also raising questions about the legal basis for the Trump administration’s escalating direct military confrontations with Syrian government forces.

But over the course of a 90-minute hearing before the Foreign Relations Committee, it was clear that policy disagreements that thwarted previous efforts to update the authorization to use military force against the perpetrators of the Sept. 11, 2001, attacks — a law that three presidents have used to justify combat against foes and in countries far beyond Al Qaeda in Afghanistan — remained daunting.

“Some members of Congress will use this debate for the singular purpose of imposing limitations on our president — it’s just a fact,” said Senator Bob Corker, Republican of Tennessee, the chairman of the committee. “Others may refuse to limit a president at war in any way. That’s a fact. And that is a wide gap to bridge.”

The hearing was the latest in a yearslong series of congressional debates over what, if anything, to do about the open-ended Sept. 11 war authorization. The executive branch has stretched the law to encompass war against enemies with only tenuous links to the original Al Qaeda, which has proved controversial, and senators disagreed Tuesday about whether it covered the Islamic State, as the Obama administration first claimed.