WASHINGTON — The House narrowly rejected a war powers resolution Thursday to halt President Donald Trump’s attacks on Iran, an early sign of unease in Congress over the rapidly widening conflict that is reordering U.S. priorities at home and abroad.

It’s the second vote in as many days, after the Senate defeated a similar measure along party lines. Lawmakers are confronting the sudden reality of representing wary Americans in wartime and all that entails — with lives lost, dollars spent and alliances tested by a president’s unilateral decision to go to war with Iran.

While the tally in the House, 212-219, was expected to be tight, the outcome provided a clarifying snapshot of political support for, and opposition to, the U.S.-Israel military operation and Trump’s rationale for bypassing Congress, which alone has the power to declare war. At the Capitol, the conflict has quickly carried echoes of the long wars in Afghanistan and Iraq, and many Sept. 11-era veterans now serve in Congress.

“Donald Trump is not a king, and if he believes the war with Iran is in our national interest, then he must come to Congress and make the case,” said Rep. Gregory Meeks, the top Democrat on the House Foreign Affairs Committee.

The House also approved a separate measure affirming that Iran is the largest state sponsor of terrorism.

Trump’s Republican Party, which narrowly controls the House and Senate, largely sees the conflict with Iran not as the start of a new war, but the end of a government that has long menaced the West. The operation has killed Iran’s Supreme Leader Ayatollah Ali Khamenei, which some view as an opportunity for regime change, though others warn of a chaotic power vacuum.

Republican Rep. Brian Mast of Florida, chairman of the House Foreign Affairs Committee, publicly thanked Trump for taking action against Iran, saying the president is using his own constitutional authority to defend the U.S. against the “imminent threat” the country posed.

Mast, an Army veteran who worked as a bomb disposal expert in Afghanistan, said the war powers resolution was effectively asking “that the president do nothing.”

For Democrats, Trump’s attack on Iran, influenced by Israeli Prime Minister Benjamin Netanyahu, is a war of choice that is testing the balance of powers in the Constitution.

“The framers weren’t fooling around,” said Rep. Jamie Raskin, D-Md., arguing that the Constitution is clear that only Congress can decide matters of war. “It’s up to us.”

While views in Congress are largely falling along party lines, there are crossover coalitions. The war powers resolution, if signed into law, would have immediately halted Trump’s ability to conduct the war unless Congress approved the military action. The president would likely veto it.

After launching a surprise attack against Iran on Saturday, Trump has scrambled to win support for a conflict that Americans of all political persuasions were already wary of entering. Trump administration officials spent hours behind closed doors on Capitol Hill this week trying to reassure lawmakers that they have the situation under control.

Six U.S. military members were killed over the weekend in a drone strike in Kuwait, and Trump has said more Americans could die. Thousands of Americans abroad have scrambled for flights, many lighting up phone lines at congressional offices as they sought help trying to flee the Middle East.