WASHINGTON - The U.S. Senate could vote as soon as Thursday on a resolution directing President Donald Trump to end U.S. military involvement in the war with Iran unless Congress authorizes the conflict.

Reuters reported Thursday morning that Senate aides said the vote could take place as soon as Sept. 24, as lawmakers prepare to leave Washington ahead of the November midterm elections.

No Senate vote on the resolution had been completed as of late Thursday morning.

The measure concerns Congress' authority under the War Powers Resolution and would direct the president to remove U.S. Armed Forces from hostilities with Iran unless Congress has approved a declaration of war or a specific authorization for the use of military force.

Resolution already passed House

The measure scheduled for Senate consideration is H.Con.Res.89.

The House approved that resolution July 23 by a vote of 214-208.

Four Republicans joined Democrats in supporting the measure at that time, while most Republicans opposed it.

The resolution was subsequently sent to the Senate and referred to the Foreign Relations Committee.

Senate leaders have now agreed that H.Con.Res.89 will be discharged from the committee and brought before the full chamber.

Under the agreement announced this week, the Senate will allow up to six hours of debate before voting on adoption.

The vote must occur no later than Oct. 2, although aides told Reuters it could happen as early as Thursday.

Thursday vote not yet formally scheduled

The Senate's official Thursday schedule listed two morning votes involving the Protect College Sports Act and said additional roll-call votes were possible later in the session.

The Iran resolution was not listed with a specific voting time on the published morning schedule.

That means the Senate could still take up the measure Thursday, but the timing remained unsettled as lawmakers began the day's session.

Repeated congressional votes on the war

Congress has repeatedly considered efforts to restrict or end U.S. military action against Iran since the conflict began in February.

Reuters reported that the Senate has voted on Iran-related war powers resolutions 13 times, with two receiving majority support.

The House has held six such votes, with three supporting efforts to end the conflict.

Only one previous Iran war powers resolution has passed both chambers, according to Reuters.

The White House did not treat that earlier concurrent resolution as requiring an end to military operations.

Congress and White House remain divided

Supporters of the current resolution argue that prolonged military operations against Iran require explicit congressional authorization.

Opponents have defended the president's authority as commander in chief and have argued that restricting military operations could undermine U.S. security objectives during an active conflict.

The Constitution gives Congress the power to declare war, while the president serves as commander in chief of the armed forces.

The War Powers Resolution of 1973 was enacted to establish procedures governing the use of U.S. forces when Congress has not formally declared war.

Political pressure increasing

The latest vote is being prepared less than six weeks before the Nov. 3 midterm elections.

Reuters reported that some Republican candidates and lawmakers have recently expressed greater concern about the duration and economic consequences of the Iran conflict.

A Reuters/Ipsos poll released this week found that 34% of U.S. adults surveyed approved of the strikes on Iran.

The conflict has also coincided with higher fuel prices, including record diesel prices that have prompted separate discussions inside the administration about domestic fuel supplies.

House voted again last week

The House approved another Iran war powers resolution on Sept. 15 by a vote of 220-204.

Seven Republicans joined all voting Democrats in supporting that measure.

That vote represented the House's third successful attempt to direct an end to U.S. involvement in the conflict without congressional authorization.

The Senate action currently being prepared involves the earlier H.Con.Res.89, which already passed the House in July.

What happens next

Senate leaders have guaranteed consideration of H.Con.Res.89 no later than Oct. 2.

A vote could occur Thursday if leaders schedule the required debate and subsequent roll call.

Until that vote occurs, the Senate has not taken a new position on the resolution.

The American Desk will update this report if the Senate begins debate or records a vote on the measure.