Democrats in Congress are exploring a lawsuit against President Donald Trump if he continues the war in Iran beyond Friday’s legal deadline without obtaining congressional authorization, multiple sources familiar with the matter tell TIME, setting up a potential constitutional clash over presidential war powers as Congress prepares for another vote this week.

The internal discussions, which have not been previously reported, were described by lawmakers as still in the early stages but could intensify in the coming weeks if the President presses ahead with military operations after a critical 60-day deadline expires on May 1.

Interviews with dozens of Democrats in the House and Senate show a party increasingly grappling with how to enforce limits on Trump’s war with Iran, convinced that the looming 60-day mark under the War Powers Resolution may be their strongest opportunity yet to challenge a war they say was launched illegally and sustained without meaningful congressional oversight. Several of those Democrats tell TIME that Congress would have a credible legal claim if Trump ignores the statute, though most argued they should first exhaust legislative remedies before turning to the courts.

“Legal action has to be explored,” says Sen. Richard Blumenthal of Connecticut, an attorney who sits on the Judiciary and Armed Services committees and unsuccessfully sued Trump in his first term. “He has to be confronted with illegality, and the court is one way to do it.”

Rep. Ted Lieu of California, vice chair of the House Democratic Caucus, echoed the belief that Congress should explore litigation if Trump ignores the 60-day deadline, which he argued would improve their chances of securing standing, an initial hurdle that must be cleared before a lawsuit can move forward. “I’m absolutely in favor of a lawsuit,” he says. “I believe we would have a very strong argument that we would have standing.”

“If we don't have standing,” Lieu adds, “then it would mean that, basically, this law could never be enforced.”

The emerging discussions mark the clearest sign yet that Democrats, repeatedly blocked in their attempts to restrain the war through floor votes, are searching for new ways to force a constitutional reckoning over who decides when America goes to war.

For nearly eight weeks, Republicans have turned back repeated Democratic efforts to compel an end to hostilities or require formal authorization. Under the War Powers Act of 1973, presidents must terminate military operations after 60 days unless Congress has voted to declare war or passed legislation to authorize the use of force. The law allows for a single 30-day extension, but only if the president certifies to Congress in writing that additional time is necessary to ensure the safe withdrawal of U.S. troops. So far, Congress has not approved any authorization for the use of military force tied to Iran and the White House has given no public indication that it plans to seek authorization from Congress ahead of that deadline.

The U.S. military campaign, which began on Feb. 28, will reach the 60-day mark on April 29, but Trump has until May 1 to seek congressional approval to continue operations in Iran since he formally notified Congress of the strikes on March 2, when the 60-day clock is triggered. A handful of Republicans previously told TIME that May 1 was a pivotal turning point that the President and Republican leadership needed to take seriously.

Trump is also currently weighing an offer from Iranian officials to reopen the Strait of Hormuz while postponing negotiations over Iran’s nuclear program. Democrats’ strategy over a lawsuit might shift if the U.S. were to return the conflict to some form of a ceasefire by accepting that offer before Friday.

Rep. Pete Aguilar of California, the chair of the House Democratic Caucus, says that leadership’s focus on the Iran War remained squarely on legislative options, despite members discussing legal action. “That’s the only strategy that we’re considering at this point,” he says of additional War Powers votes. Asked whether Democratic leadership was considering suing the President if he did not request congressional authorization for the war beyond May 1, he replied: “At the moment, we’re concerned with what’s on the board this week.” 

Sen. Adam Schiff of California, an attorney and member of the Judiciary Committee, says he plans to force another War Powers Resolution vote at the end of this week, timing it to coincide with the 60-day mark. “Republicans who have been saying that mark is important to them, they'll have an opportunity to demonstrate that in the vote on resolution,” he says.

While it’s unclear how Republicans will ultimately vote, Schiff urged caution about relying on the courts. “The Supreme Court has been very selective about offering Congress standing to any litigation,” he says. “It's not a strategy I would want to rely on… We can pass a War Powers Resolution. We can vote against authorizing any additional funding for the war. Those are the steps I would take before contemplating litigation.”

Many Democrats also insisted that Trump was already in violation of the law because he launched strikes before consulting Congress, and that legal action could be taken regardless of the looming deadline. “The 60 days actually means no difference in this circumstance, because the war was done illegally,” says Sen. Andy Kim of New Jersey. “It’s as illegal on day 60 as it was on day one.”

Yet even many Democrats who view the war as unlawful from the outset see the deadline as a pivotal moment because several Republicans have signaled that they may not support continuing military operations beyond it without a vote of Congress. “I think we’re gonna have the votes first and go that way,” says Rep. Glenn Ivey of Maryland, who added, “all cards are on the table.”

Questions Over Who Can Sue

Whether the courts would hear such a case remains a matter of debate. Federal judges have repeatedly declined to resolve clashes between Congress and presidents over military force, often ruling that such disputes present “political questions” better settled by the elected branches, or asserting that the lawmakers lacked standing to sue.

Blumenthal has experienced it personally. During Trump’s first term, he joined roughly 200 Democratic lawmakers in an Emoluments Clause lawsuit accusing the President of accepting improper financial benefits while in office. An appeals court ruled that the lawmakers lacked standing because they did not represent a majority of either chamber.

Blumenthal said the Iran case could be different. “Congress would definitely have standing,” he told TIME, though he acknowledged that much could depend on how the suit was structured. He noted that his earlier case had been brought by members rather than by Congress as an institution.

That distinction is central to the current debate. Some Democrats believe only a lawsuit authorized by one or both chambers would have the best chance of surviving in court. But because Republicans control Congress, such authorization is a nonstarter.

Others argue that the injury here is more direct than in past cases: if lawmakers cannot sue to enforce a statute specifically designed to preserve Congress’s war powers, then the law may effectively be unenforceable.

Sen. Mark Kelly of Arizona, a member of the Armed Services committee, says his office had already begun examining the question of what happens if Trump continues the war while ignoring the deadlines set in the War Powers Resolution. “It would be a violation of a law that Congress passed,” Kelly says. “I would think we have standing.”

In a recent opinion essay in the New York Times, Erwin Chemerinsky, dean of the University of California at Berkeley law school, wrote that if the war continues past Friday without congressional approval, it would be “clearly illegal” under the War Powers Resolution. He argued that “it is the obligation of the federal courts to say so,” and that suits should be brought, including by service members and by members of Congress.

However, Chemerinsky acknowledged that courts have often dismissed prior war-powers suits, decisions that have effectively made Congress’s war authority meaningless. In 1982, for example, a federal district court dismissed a lawsuit by members of Congress that challenged U.S. military assistance to El Salvador under the Reagan Administration, and in 2002 another federal district court dismissed an effort by lawmakers to block the Bush Administration from moving forward with the Iraq invasion, finding that the questions raised were political in nature and “beyond the authority of a federal court to resolve.” A similar outcome followed in 2011, when a challenge to U.S. military operations in Libya under President Barack Obama was also dismissed.

Without judicial enforcement, Chemerinsky wrote, “there are realistically no checks on the president’s ability to unilaterally wage war.”

In practice, however, presidents of both parties have often found ways to continue military operations beyond the 60-day limit without direct court intervention. President Bill Clinton in 1999 continued a NATO-led air campaign in Kosovo past the 60-day deadline even though Congress never explicitly authorized the operation—though it did pass a spending bill that provided funding for it.

Sen. Tim Kaine of Virginia, who has spearheaded Democrats’ efforts to push War Powers resolutions, says lawmakers are exploring multiple fronts beyond litigation to influence Trump’s next steps in Iran, including blocking future supplemental requests, the annual defense bill, and appropriations for the next fiscal year. “There’s a couple of different angles right now,” he says.

That broader strategy reflects a growing recognition among Democrats that even a successful lawsuit might move too slowly to shape events on the ground. Still, the legal threat itself could carry political force. It would underscore Democratic claims that Trump is defying not only Congress but a law enacted to prevent unilateral wars. And with some Republicans already signaling unease about extending the conflict past 60 days, Democrats see an opening.

“I think right now that talk is too far away,” says Democratic Sen. Tammy Duckworth of Illinois, referring to a lawsuit. “Some of my Republican colleagues have expressed that they would not vote to fund this war past the 60-day mark. So I want to show them the grace to cast that vote.”