Democratic House Speaker Nancy Pelosi plans to hold votes this week to limit President Donald Trump’s military action against Iran as tensions escalate in the Middle East following the targeted U.S. assassination of a top Iranian general.

Pelosi’s move comes as Minnesota U.S. Rep. Ilhan Omar and other Democrats already have jumped ahead with a similar resolution condemning the Trump-ordered killing of Gen. Qassem Soleimani and blocking the use of further U.S. military force against Iran without congressional authorization.

The looming vote testing Trump’s war powers could deepen Democrats’ ongoing confrontation with Trump, with an impeachment trial on the horizon in the Senate. But any move to restrain Trump on Iran remains uncertain in the Republican-led Senate, meaning a House resolution could be largely symbolic.

“Last week, the Trump administration conducted a provocative and disproportionate military airstrike targeting high-level Iranian military officials,” Pelosi said in a letter to House Democrats on Sunday. “This action endangered our service members, diplomats and others by risking a serious escalation of tensions with Iran.”

The resolution Omar co-sponsored with Rep. Barbara Lee, D-Calif., affirms that Congress alone can declare war. It would require that Trump withdraw from any hostilities against Iran within 30 days unless there is a declaration of war or Congress authorizes him to use force. Their draft would not block the U.S. from defending itself against an attack.

“Let’s not mince words: the assassination of Qassem Soleimani was an act of war undertaken without Congressional authorization, in violation of the Constitution of the United States of America. … We in Congress must exercise our Constitutional duty — and do everything in our power to stop another disastrous war,” Omar said in a statement.

Omar’s measure is identical to one that Virginia Democrat Tim Kaine proposed Friday in the Senate. Omar spokesman Jeremy Slevin said Omar and Lee are waiting to see how their resolution differs from the specifics in the proposal Pelosi announced, which will be led by Rep. Elissa Slotkin, D-Mich.

Pelosi indicated in her letter that Slotkin’s measure will be similar to Kaine’s.

Republicans in Congress have largely backed Trump’s actions. But Democratic lawmakers and presidential candidates have raised questions about the assassination, including Minnesota U.S. Sen. Amy Klobuchar. She said that while Soleimani directed destabilizing action throughout the Middle East, including attacking U.S. forces, the timing and manner of Trump’s action are concerning.

“Our immediate focus needs to be on ensuring all necessary security measures are taken to protect U.S. military and diplomatic personnel in Iraq and throughout the region. The Administration needs to fully consult with Congress on its decisionmaking, response plans, and strategy for preventing a wider conflict,” Klobuchar said in a statement.

Congressional leadership was not informed of the White House’s plan to carry out the drone strike Thursday to kill Soleimani. Instead, Trump formally notified Congress on Saturday about the assassination, within the 48-hour deadline in which he is required to report such action.

However, the notification contained only classified information, and Democrats have since been pressing for a public explanation of the decision. Administration officials are expected to brief Congress members this week on the killing.

Past presidents at least signaled a nod to the legislative branch, knowing they would need to ask Congress to pay for military operations. It’s one way the founders sought to keep the chief executive in check.

But Congress has allowed its role to erode since the passage of Authorization for Use of Military Force in 2001 to fight terrorism after the Sept. 11 attacks, and passage of another AUMF for the invasion of Iraq in 2002.

The fallout from those votes has deeply divided Congress, with many lawmakers, particularly Democrats, now saying they were mistakes. Yet lawmakers have not acted on whether to repeal or change those authorities.

The efforts by Pelosi and Omar to reassert Congress’ sole power to declare war came amid a ratcheting up of the rhetoric between the U.S. and Iran. On Sunday, Trump wrote on Twitter that if Iran retaliates for the killing of Soleimani, the U.S. has targeted 52 locations, including Iranian cultural sites, that it will hit “very fast and very hard.”

Omar responded to Trump’s message in a tweet: “The President of the United States is threatening to commit war crimes on Twitter. God help us all!”

She and other Democrats have decried the president’s actions on Iran in recent days. Republican lawmakers have responded by defending Trump’s legal authority to target Soleimani.

Texas Sen. Ted Cruz tweeted at Omar, saying that according to former President Barack Obama’s Department of Defense, “Qassem Soleimani was a terrorist directly responsible for the murder of over 500 US service men & women. Why are congressional Dems outraged that he’s finally dead.”

White House counselor Kellyanne Conway also defended Trump’s actions to reporters Monday.

“He’s the commander in chief,” Conway said. “And he did what a responsible, strong — not weak — commander in chief does when faced with the opportunity to take out one of the, if not the, world’s most wanted terrorist.”