he US Senate on Tuesday rejected a bipartisan bid to end American involvement in Yemen s civil war, voting down a rare effort to overrule presidential military authorization.

The vote addressing American war powers had aimed to shut down US military involvement in Yemen within a month unless Congress formally authorized continued involvement.

Senators voted 55-44 to kill the bid after the Senate s Republican leadership and key figures from both parties on the Senate Foreign Relations Committee came out against it.

But the vote served to highlight US involvement in a three-year-old military conflict in the Middle East s poorest country, which the United Nations has described as the world s largest humanitarian disaster.

The US has provided weapons, intelligence and aerial refueling to the Saudi-led coalition supporting Yemen s government against Iran-backed rebels.

Some US lawmakers have long expressed concern about the conflict, where civilian casualties from coalition air strikes have drawn criticism from rights groups.

The resolution, sponsored by independent Senator Bernie Sanders and 14 others, forced the first-ever vote in the Senate to withdraw US armed forces from what sponsors labelled an “unauthorized” war.

“If Congress wants to go to war in Yemen or any place else, vote to go to war,” Sanders said Tuesday.

“That is your constitutional responsibility. Stop abdicating that responsibility to a president.”

Supporters of the Senate measure argued that Yemen was the latest hot spot where the Pentagon was engaged under an authorization to use military force (AUMF) that Congress first passed on September 14, 2001, three days after the deadly attacks on New York and Washington by Al-Qaeda hijackers.

Since then, presidents George W. Bush, Barack Obama and now Donald Trump have relied on the order s authority, along with a subsequent AUMF in 2002, as the basis for operations against armed Islamist groups.

While the vote failed, it put deliberations over a new AUMF into the congressional spotlight.

Senate Foreign Relations Committee chairman Bob Corker said it was preferable to go through standard committee procedure rather than force an extraordinary floor vote.

“Let us work our will in the appropriate way,” the Republican Corker told colleagues.

He explained that the committee would hold hearings on Yemen next month and on April 19 would consider a new AUMF that could authorize US involvement there.