How Congress can limit Trump's power with the Iran conflict

The House is poised to vote on Thursday on an Iran war powers resolution aimed at restraining the President's military action against Iran, House Speaker Nancy Pelosi announced on Wednesday.

Trump appeared to signal a deescalation of tensions with Iran earlier on Wednesday in the wake of Iran's retaliatory attacks against Iraqi bases housing US troops, which came after a US airstrike killed Iranian commander Qasem Soleimani.

But despite that, Pelosi said in her statement announcing the vote that "members of Congress have serious, urgent concerns about the administration's decision to engage in hostilities against Iran and about its lack of strategy moving forward."

Pelosi had previously said that the House resolution would be similar to a measure introduced in the Senate by Democratic Sen. Tim Kaine of Virginia, which calls for the removal of US armed forces from hostilities with Iran not authorized by Congress.

What is the War Powers Resolution?

In their effort to restrain US conflict with Iran, congressional Democrats are invoking the War Powers Resolution, otherwise known as the War Powers Resolution of 1973 or the War Powers Act.

Under the Constitution, the President acts as commander-in-chief of the US Army and Navy, but Congress has the power to declare war.

The War Powers Resolution further stipulates parameters of presidential and congressional war powers, including imposing procedural requirements to ensure that presidents keep Congress apprised of military decisions as well as provisions that provide Congress with a mechanism to suspend military operations initiated by the President in certain circumstances.

It was enacted after Congress overrode a veto from then-President Richard Nixon and is aimed at reining in a president's authority to engage the US in military action without congressional approval.

What does it do?

The resolution requires the President to submit a report to Congress within 48 hours of engaging US armed forces in hostilities in the absence of a declaration of war.

Once a report is submitted to Congress, the President must halt the military action within 60 calendar days with an additional 30-day withdrawal period if necessary unless Congress declares war or enacts a specific authorization for the use of US armed forces with limited exceptions.

The Trump administration sent Congress a formal notification on Saturday regarding the drone strike that killed Soleimani in accordance with the War Powers Resolution.

It was classified, however, and Pelosi said in a statement that the notification "raises more questions than it answers," pointing to the decision to classify it as a "highly unusual" move that "compounds our many concerns, and suggests that the Congress and the American people are being left in the dark about our national security."

What are the House and Senate resolutions to limit conflict with Iran?

The House and Senate are both poised to take up war powers resolutions.

In the Senate, Kaine introduced his war powers resolution last week along with Democratic Sen. Dick Durbin of Illinois. As a war powers resolution, the measure is privileged, which means that the Republican-controlled Senate will have to hold a vote.

Kaine has made clear that he does not support a war with Iran, but he has also said that it is the responsibility of Congress to publicly debate and vote on the possibility of military action to prevent the President from acting unilaterally.

The resolution will "give all 535 members of Congress the opportunity to declare where they are on the advisability of a war with Iran," Kaine said on Monday.

The resolution directs the President to remove US forces from hostilities with Iran no later than 30 days after the resolution is enacted absent a declaration of war by Congress or passage of a new authorization for use of military force, a type of measure that lawmakers can approve to green-light military action.

The House resolution will be led by Democratic Rep. Elissa Slotkin of Michigan, a former CIA analyst and senior Defense Department official.

In an interview with CNN's Christiane Amanpour on Tuesday, Slotkin was asked what she hopes the resolution will achieve.

"I think the intent of it is that we just abide by the constitution, and the constitution was very, very clear about authorization of military force," Slotkin said.

"The President has the responsibility to come back here and have a real conversation with the American people out in the public, with the US Congress as our founders intended," Slotkin added.

Even as the military conflict with Iran appeared to have deescalated on Wednesday, Kaine said that he will continue to press ahead with his effort to limit Trump's authority on Iran.

He added, however, that the timing may be complicated by the fact that it's uncertain when a Senate impeachment trial will begin. But since it's privileged, the Senate must vote on it.

"What we learned from the last 18 months is ... this thing has been going up and down cycles ... and deliberation is the antidote to unnecessary escalation," Kaine said of conflict with Iran.

Has Congress taken action before to rebuke Trump over war powers?

Last year, the House and Senate passed a war powers resolution to curtail US military support for a Saudi-led war in Yemen, a vote seen as a rebuke of Trump's Middle East policies.

Ultimately, however, the Senate failed to override a presidential veto of the bipartisan measure.

The Democratic-controlled House, however, is expected to have the support needed to clear an Iran war powers resolution, but it is unlikely that lawmakers would have the votes needed to override a veto on a war powers resolution related to Iran.

It also not yet clear if such a resolution would have the votes to pass in the Republican-led Senate Senate. But whatever the outcome, the introduction of the measure ensures there will be an ongoing congressional debate over the President's escalation of hostilities with Iran.