Over nearly eight weeks of war in Iran, Republicans in Congress have turned back repeated efforts by Democrats to halt the operation and force President Trump, who began the conflict without congressional authorization, to consult with lawmakers on the military campaign.
But some in the G.O.P. have signaled that a key statutory deadline in the coming weeks could be an inflection point when they will expect the president to either wind down the conflict or seek congressional approval to continue it.
Democrats have tried and failed several times to invoke a provision of the 1973 War Powers Resolution, a law aimed at curbing a president’s ability to wage war without congressional approval, to challenge the conflict in Iran. The latest defeat came on Wednesday, when Senate Republicans blocked such a measure for the fifth time since the war began.
Yet the law also establishes a set of deadlines, the first of which is coming on May 1, that could increase the pressure on the Trump administration in the coming days. Here is what the law says about how long a president can continue to direct U.S. forces in a conflict without congressional approval.
The 60-Day Mark
When the United States began joint strikes with the Israeli air force on Feb. 28, the president said he was acting under his authority as commander in chief to protect U.S. bases in the Middle East, and to “advance vital United States national interests.” He said the action was taken in “collective self-defense of our regional allies, including Israel.”
Many Democrats disputed that justification and have continued to argue that Mr. Trump acted illegally. White House officials and most Republicans on Capitol Hill say he is operating within the bounds of the war powers statute, which sets a 60-day clock for a president to remove American forces from hostilities without congressional authorization to use military force.
Although the war began at the end of February, Mr. Trump formally notified Congress of the operation on March 2, starting the 60-day period that ends on May 1.
Some Republicans have already signaled they will not support any extension beyond 60 days.
Senator John Curtis, Republican of Utah, wrote in an opinion essay earlier this month that he “will not support ongoing military action beyond a 60-day window without congressional approval.”
Other Republicans, including Representative Brian Mast of Florida, who chairs the Foreign Affairs Committee, warned that the president could lose significant support if the conflict continued into May.
Moments after Republicans just barely blocked a war powers resolution in the House last week, Mr. Mast said there could be “a different vote count after 60 days,” alluding to the May 1 deadline.
A 30-Day Extension
Under the statute, once the initial 60-day deadline passes, the president’s options for continuing a military campaign without congressional approval become limited. At that point, Mr. Trump would effectively have three choices: seek congressional authorization to continue the campaign, begin winding down U.S. involvement or give himself an extension.
The law allows a one-time, 30-day extension of the deployment if the president certifies in writing that additional time is necessary to facilitate the safe withdrawal of U.S. forces, but it does not grant authority to continue waging an offensive campaign.
Congress Can Authorize the War
Lawmakers also have the option at any time of granting explicit permission for Mr. Trump to continue the operation by passing an authorization for the use of military force. Such measures have become the primary way Congress approves military campaigns short of a formal declaration of war, something that has not been done since World War II.
While Republicans have largely united in blocking Democrats’ attempts to halt the war, it is unclear whether the same unity exists when it comes to affirmatively authorizing the conflict.
Senator Lisa Murkowski, Republican of Alaska, has said she is working with a group of senators on a formal authorization for the use of military force against Iran, but has yet to introduce the resolution.
Congress has not voted in favor of using military force since 2002, when lawmakers authorized it against Iraq.
Ms. Murkowski was an early critic of the administration’s lack of transparency around the objectives, costs and timeline for the war, and said that her goal with an authorization vote would be to reassert congressional authority and require the administration to be held to firm parameters for the operation.
Why Trump Might Ignore the Deadlines
Administrations led by presidents of both parties have long argued that the Constitution gives broad authority to the commander in chief, meaning that the limits the war powers law places on the president are unconstitutional.
In 2011, President Barack Obama continued a military engagement in Libya beyond the 60-day mark, arguing that the law did not apply because “U.S. operations do not involve sustained fighting or active exchanges of fire with hostile forces, nor do they involve U.S. ground troops.” Though that prompted bipartisan backlash at the time, some lawmakers anticipate that the Trump administration could make a similar argument about Iran.
During his first term, Mr. Trump similarly balked at the law in 2019 when he vetoed a bipartisan resolution both chambers had passed that sought to end American military involvement in Saudi Arabia’s civil war in Yemen. He argued then that the measure was an “unnecessary, dangerous attempt to weaken my constitutional authorities.”
Still, ignoring the deadline could pose a political problem for the G.O.P., which so far has given the administration broad latitude to carry out the war without congressional involvement, including any formal oversight.
“Many Republicans are on record having set the 60-day mark as somehow legally important,” said Senator Chris Murphy of Connecticut, who has been among the Democrats offering resolutions aimed at limiting the president’s ability to continue the war without congressional authorization. “So I do think it will be harder for Republicans to continue to look the other way once we are out of the 60 days.”
