Republicans Waited to Challenge Trump on the Iran War. Now It May Be Too Late.

The Republican-led Congress has missed a crucial window to play a role in the U.S. military operation in Iran, with G.O.P. lawmakers who deferred to President Trump for months on the war now hand-tied by their reticence to challenge him and his administration’s efforts to evade congressional oversight or input.

Since Mr. Trump began the war on Feb. 28, Republicans have consistently blocked Democratic efforts to halt the hostilities and force the president to win authorization from Congress, arguing that such a move would undermine him in the fight in the Middle East. They have also hung back from putting forth any legislation that would bless the mission and lay out goals, limits and a timeline for withdrawal.

That posture — the latest move by Republicans to cede congressional power to the president — has effectively allowed Mr. Trump to run out the clock for quick action by Congress on the conflict.

As their reservations about the war have grown in recent weeks, some Republicans have considered trying to rein in the operation with an authorization that would lay out narrow objectives and criteria for an eventual exit. But they missed a 30-day deadline after the start of the war to force consideration of such a bill.

And the White House this month steered around another statutory milestone of 60 days, which fell on May 1, for Mr. Trump to seek permission from Congress to continue the conflict or begin to withdraw forces. His team argued that the 60-day clock had stopped because the cease-fire between the United States and Iran had terminated the conflict, and claimed that the U.S. forces imposing a blockade in the Strait of Hormuz had begun a separate operation called Project Freedom.

That has left critics with fewer tools at their disposal for challenging the military action in the Middle East, and thrust Republicans in Congress into the perilous position of owning an unpopular war during a challenging midterm election year in which they were already in an uphill fight to keep their majorities.