“It’s the law,” Republican Sen. James Lankford of Oklahoma tells TIME when asked whether Congress should authorize the war after that point. “They should.”

The White House did not respond to a request for comment on whether Trump plans to seek congressional authorization if the war extends beyond the 60-day window. Trump has at times avoided using the word “war,” describing the conflict in Iran as a “military operation” or an “incursion,” and has suggested he wouldn’t have to seek congressional authorization.

But virtually all Democrats and many Republicans do see that 60-day deadline as unalterable, meaning they expect Trump to formally request congressional authorization. 

Democrats are approaching the deadline as a moment when Republicans can no longer sidestep questions about Congress’ oversight role over the war. Sen. Tim Kaine of Virginia, who has spearheaded Democrats’ efforts to push War Powers resolutions to end the Iran War, tells TIME that Senate Democrats are preparing to force additional such votes before and after the 60-day deadline, betting that the Republican calculus should shift as the statute’s requirements move from hypothetical to immediate. “Some are suggesting that this is a watershed moment for them and I hope that that’s true,” Kaine says of the GOP.