A resolution to rein in US President Donald Trump’s authority to wage war with Iran has failed for the fourth time in the US Senate, where lawmakers have pledged to introduce the measure weekly.

The vote was the first since the US and Iran agreed to a two-week ceasefire last week. Subsequent talks in Islamabad, Pakistan, failed to yield a more lasting agreement, although both sides have signalled they are open to a second round.

Prior to the fighting pause, US President Donald Trump had repeatedly threatened to strike civilian infrastructure in Iran. His threat on April 7 that a “whole civilisation will die tonight”, just hours before an agreement had been reached, stoked further calls for Congress to constrain Trump on the war.

As with past votes, the resolution on Wednesday failed mostly along party lines, 47-52, with one Republican, Rand Paul, voting in favour and one Democrat, John Fetterman, voting against.

Supporters of the resolution have maintained that Trump acted outside of constitutional authority in launching the war alongside Israel on February 28. The US Constitution reserves the decision to go to war for Congress, with presidents only able to unilaterally launch operations in instances of immediate self-defence.

The Trump administration, meanwhile, has offered a carousel of explanations for going to war, including arguing that the totality of Iran’s actions since the Islamic revolution in 1979 represented an imminent threat to the US.

Speaking before Wednesday’s vote, US Senator Chris Murphy called the conflict a “bungled, mismanaged war” that has failed to achieve several of the administration’s stated goals.

He further decried a lack of transparency from the Trump administration and oversight from Republicans in Congress.

“We should not fail to note how extraordinary it is that our Senate Republican leadership has declined to do any oversight of a war that is costing billions of dollars every week, that has already led to the loss of over a dozen American lives, that has erupted a regional war throughout the Middle East, and is literally melting down economies all over the world,” Murphy said.

Senator Jim Risch, a Republican, maintained Trump was acting within his authority as president, dismissing the measure as “a same old, same old”.

“It says President Trump: ‘Put your tail between your legs and run.’ That’s what this resolution says,” he said.

“Not only does [Trump] have the right to do this, he has the duty to do this. He took an oath to defend the people of the United States of America,” he said.

The US House of Representatives was expected to vote on its own resolution this week, with passage in the chamber considered more plausible, particularly given growing wariness of the war among some Republicans.

The success of the resolution in either chamber would be largely symbolic. Even if it passed both the House and the Senate, it could be vetoed by Trump. Both chambers would then need a likely insurmountable two-thirds vote to overcome the veto.

However, lawmakers could face a larger test at the end of April, when the war hits its 60-day mark. Under the War Powers Act of 1973, the US Congress must authorise the military action at that point or approve a 30-day extension.

Otherwise, Trump would be legally required to begin withdrawing forces.

US blockade continues

On Wednesday, US Central Command (CENTCOM) said that no ships entering or exiting Iranian ports had successfully crossed the US blockade in the Strait of Hormuz over the last 48 hours. CENTCOM said that nine vessels had complied with US military commands to turn around.

In a separate statement, the US Navy said it was warning ships that “vessels will be boarded for interdiction and seizure transiting to or from Iranian ports”.

US Treasury Secretary Scott Bessent, meanwhile, said Washington was preparing a new raft of actions that would be the “financial equivalent” of military attacks. The US had lifted some sanctions on Iran amid the war to lower soaring global energy prices.

Speaking to reporters, White House spokesperson Karoline Leavitt said the Trump administration had not formally requested an extension of the two-week ceasefire, which is set to end next week.

She struck an optimistic tone on the prospect of a second round of US-Iran talks in Islamabad.

“At this moment, we remain very much engaged in these negotiations, in these talks,” she said.

Meanwhile, Iran’s state-owned television channel reported that a high-level Pakistani delegation had arrived in Tehran to coordinate a new round of talks.

Still, Major-General Ali Abdollahi, the commander of the Khatam al-Anbiya Central Headquarters of the Islamic Revolutionary Guard Corps (IRGC), warned that the ongoing naval blockade could end the fragile pause in fighting.

“If the aggressor and terrorist US seeks to continue its illegal action of imposing a naval blockade in the region and to create insecurity for Iran’s commercial vessels and oil tankers, this action by the US will constitute a prelude to a violation of the ceasefire,” he said. (Al Jazeera)

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