An attempt by House Democrats to pass a long-shot resolution on Thursday curtailing Donald Trump’s war powers over Iran failed after the Republican pro forma speaker, Chris Smith, did not recognize lawmakers from the opposite party on the floor.

The vote, scheduled for Thursday morning, used a procedure called unanimous consent, which is a shortcut that allows legislation to pass the chamber instantly, without debate or a formal tally, so long as not a single member objects. Any one lawmaker can kill the resolution by simply objecting, and Republicans were expected to do exactly that.

Glenn Ivey, a Democratic representative from Maryland, attempted to be recognized on the floor, but Smith ended the session immediately. There were a handful of other Democrats in attendance who objected loudly.

The move from Republicans was expected to be blocked, but its introduction was a signal of unease on Capitol Hill about a Middle Eastern conflict on pause with no clear endgame.

The temporary ceasefire announced on Tuesday is already showing serious cracks. Israel has continued to strike Lebanon claiming it is hunting Hezbollah, though Iran insists it was covered by the truce – a claim both the US and Israel reject. Lebanese authorities say the latest wave killed at least 254 people and injured another 837 people, and totally levelled buildings in central Beirut.

Iran has reportedly halted oil tanker traffic through the strait of Hormuz again, according to Iran’s Fars News, just hours after the first vessels were allowed through. No official ceasefire text has been released, and JD Vance has called it a “fragile” ceasefire. The UN secretary-general warned that continued Israeli military activity in Lebanon “poses a grave risk” to the deal.

Against that backdrop, Hakeem Jeffries, the House minority leader, pressed ahead. In a letter to colleagues on Wednesday, he expressed significant doubt in the ceasefire.

“A two-week ceasefire is woefully insufficient,” Jeffries said. “Accordingly, we have demanded that the House come back into session immediately in order to vote on our resolution to permanently end the war in the Middle East.”

The House is on a two-week recess and will not return for formal votes until 14 April.

Republican crossover support for a war powers resolution remains elusive. Representative Nancy Mace, who floated supporting Democrats last month, is now considered unlikely by members of both parties to break ranks.

Representative Don Bacon, a Republican and retired one-star general who backed a war powers measure limiting Trump’s Venezuela policy earlier this year, told Politico he would “listen” before adding: “I want us to defeat Iran. They have murdered Americans for 47 years.”

Meanwhile, Democrat Chuck Schumer, the Senate minority leader, said Wednesday that the Senate would vote on an Iran war powers resolution when they return to Washington next week.