In its eighth war powers resolution vote since the United States went to war with Iran, the U.S. Senate has advanced legislation seeking to curb President Donald Trump’s ability to engage in conflict with Tehran.

Senate Democrats have repeatedly used War Power Resolution privileges to force votes on ending Trump’s use of military force in the Middle Eastern country without congressional approval and have vowed to continue to do so for as long as necessary.

In its eighth vote on the resolution Tuesday, Democrats were able to court enough Republican votes to advanced the measure in a 50-47 result, with three lawmakers not voting.

The Democratic victory is largely procedural, as it discharges the resolution from committee for floor consideration, limited debate and a final vote on whether to send it to the House for consideration.

The Democrats have slowly cobbled together a handful of Republican votes as the war and its effects on the economy drag on.

Republican Sen. Bill Cassidy of Louisiana cast the deciding vote to push the legislation over the threshold on Tuesday, days after thee 15-year-veteran lost the Republican primary to Rep. Julia Letlow, whom Trump endorsed in turning against Cassidy for voting to convict him during his second impeachment trial in 2021.

“While I support the administration’s efforts to dismantle Iran’s nuclear program, the White House and Pentagon have left Congress in the dark on Operation Epic Fury,” he said in a social media statement, referring to the Defense Department name for its military operation against Iran.

“In Louisiana, I’ve heard from people, including President Trump’s supporters, who are concerned about this war. Until the administration provides clarity, no congressional authorization or extension can be justified.”

Since the war began on Feb. 28 with the joint U.S.-Israeli attacks on Iran, Democrats have been accusing the Trump administration of waging an unlawful war, stating the Constitution mandates that only Congress can authorize such military force.

The president is required to end the use of U.S. forces after 60 days unless Congress authorizes the action or extends the deadline, which was May 1.

Trump argues the resolution effort is moot, stating the conflict is over, and pointing to the fragile cease-fire announced in April.

The cease-fire “gives you additional time,” he told reporters earlier this month, describing the Democrats behind the legislative effort as “not patriotic people.”

Sen. Tim Kaine, D-Va., the sponsor of Tuesday’s bill, said he was grateful that “enough of my colleagues stood up for the Constitution and listened to their constituents.”

“President Trump’s deeply unpopular war of choice in Iran has imposed a tremendous cost on the American people — including deaths and injuries of our service members and soaring gas prices,” he said in a statement.

The vote, he continued, sends “a strong message” to the Trump administration “that the American people aren’t interested in more war in the Middle East.”

The other three Republicans to vote in favor of the resolution were Sens. Susan Collins of Maine, Lisa Murkowski of Alaska and Rand Paul of Kentucky.

Sen. John Fetterman of Pennsylvania has been the lone Democrat to consistently vote with the Republicans on this war powers measure.