While the U.S. military campaign against Iran continues to unleash its full force, Congress is gathering to debate the president’s authority to conduct the campaign in the first place. This is striking in that previously, Congress debated for months before authorizing strikes, as it did ahead of the Iraq war.

Democrats have criticized the operation mostly on two grounds: The president does not have the authority to declare war, and the he has not clearly articulated the goals of the war or explained his endgame.

As bombs continue to drop, casualties rise and threats of retaliation are traded by both sides, the debate in Congress will test both Congress’ power to declare war and the limits of presidential authority.

“The Constitution is intended to prevent the accumulation of power in any one branch of government — and in any one person in government,” said David Janovsky, acting director of The Constitution Project at the Project on Government Oversight.

“Congress is the people’s representatives in a way that the president isn’t,” he said. “We need the people’s representatives to weigh in on whether we, the people, are going to war right now.”

Sen. Mark Warner, the leading Democrat on the Senate Intelligence Committee, said Trump “does not have the right to do this on his own.”

“When the president commits American forces to a war of choice, he needs to come before Congress and the American people and ask for a declaration of war,” Warner said on CNN’s “State of the Union.”

Republican isolationists who have chosen “America First” as their mantra have also criticized the war, accusing Trump of betraying his campaign promise to put America first.

However, with the Republicans controlling both Houses of Congress, despite some dissenters, it’s unlikely a vote against the war in Iran will win the day.