The resolution was introduced just hours after the House opened for its first post-midterm session, a timing that put Republican leaders on the defensive and thrust the party's internal divisions over the war into public view. Massie, who lost a Trump-backed primary challenge earlier this year, said Hegseth's conduct amounted to "high crimes and misdemeanors" and that he "remains a threat to the Constitution."

A vote could come by midweek, though the path forward is uncertain. House Democratic Leader Hakeem Jeffries supports the measure, and if most Democrats follow him, Massie would need only a handful of Republican defections to impeach Hegseth. If the House approves the resolution, the Senate would then decide whether to dismiss the charges or hold a trial. Republicans hold majorities in both chambers until the new Congress convenes in January, when Democrats take control.

Senate Democratic Leader Chuck Schumer endorsed the push, saying, "Hegseth must stand trial before the Senate."

Republican leaders, eager to use their final weeks in power on their own priorities, reacted with frustration. House Speaker Mike Johnson, who has tried to block the vote, said impeachment "in the middle of hostilities abroad would be a terrible, terrible look, a terrible thing for our allies and our enemies to see." Senate Majority Leader John Thune said he was unsure why the vote was being held now, adding, "We'll see what their ultimate decision is over there. We'll have to deal with it accordingly here."

President Donald Trump lashed out at Massie personally within hours of the resolution being read, calling him a "loser" who "has a lot of hatred in his heart." Trump also defended Hegseth, saying Sunday night that the secretary was "guilty of two things, basically winning two wars" and that "it's awfully hard to say let's impeach somebody who did that."

Hegseth, speaking to reporters after a speech at the Naval War College in Rhode Island, dismissed the effort as politically motivated. "There's a lot of politically motivated people who may have substantial policy disagreements, but their disagreements are with success," he said, adding that he is "happy to do it all day long" if the administration's military actions are to be litigated. He announced a rare news conference for Tuesday, his first in more than 180 days, to address the impeachment threat.

Hegseth argued the war was necessary because "someone had to confront the Iranian regime's pursuit of a nuclear weapon" and that "the choice was don't act and wish it away or take a bold move." Iran has long maintained its nuclear program is peaceful, though the International Atomic Energy Agency reports the country holds 440.9 kilograms of uranium enriched to 60% purity, a short technical step from weapons-grade levels.

The political backdrop is a midterm election that saw sweeping Republican losses, which Vice President JD Vance has partly blamed on the Iran war. About 6 in 10 voters said the U.S. made the "wrong decision" in taking military action against Iran, according to a survey of more than 100,000 voters. Hegseth has insisted "Iran is devastated," even as Iran has continued striking U.S.-used military bases in the Middle East, causing billions of dollars in damage, and disrupting commercial shipping in the Strait of Hormuz, where one-fifth of the world's oil passed before the war. Those disruptions have driven up energy prices and hit voters' pocketbooks.

Secretary of State Marco Rubio defended Hegseth at a Group of Seven gathering in Paris, saying he believes Hegseth has done "a great job" and that it is unfair for a Republican to push impeachment. "I work with him. And so I see perhaps a side of him that the media doesn't see and members of Congress may not see," Rubio said. "But I think Pete works really hard. He's incredibly smart."

The resolution's focus on the Iran war, along with references to Yemen and Venezuela, reflects a broader debate over the scope of executive war powers and congressional oversight. For Massie, a libertarian-leaning Republican who has often broken with his party on military and surveillance issues, the move is a final act in a tenure that ends in January. For Democrats, it is an early test of whether they can use their incoming majority to hold the administration accountable — and whether enough Republicans will join them before the gavel changes hands.