The US Senate voted 49-44, failing to garner the 67 votes needed to overturn Trump's veto.
The measure would have required that any military action against Iran be explicitly authorized by a declaration of war or specific authorisation for use of military force.
On 6 May, Trump vetoed a resolution that limits the US president's ability to conduct military operations against Iran without congressional approval.
Trump said the strike against Soleimani was authorised under the Authorisation for Use of Military Force Against Iraq (AUMF) 2002. Trump added that the Iran War Powers Resolution would hurt his ability to protect the United States and its allies, adding that the US president must be able to take swift action after anticipating an adversaries’ next move.
On the night of 3 January, the United States conducted a drone strike near Baghdad International Airport that killed Soleimani, a top general in Iran's Islamic Revolutionary Guards Corps (IRGC), and Iraqi Shiite military commander Abu Mahdi Muhandis, among others. Washington considered both military leaders to be behind the attack on the US embassy in Baghdad on 31 December.