Two Senate Republicans who helped block Democratic efforts to rein in President Trump's military campaign in Iran now say their support has limits, and the clock is running. Sens. Susan Collins of Maine and Thom Tillis of North Carolina each signaled this week that they could oppose continuing hostilities without congressional authorization if the conflict reaches the 60-day threshold set by the War Powers Resolution of 1973.

The warnings land at an awkward moment. Senate Republicans just defeated a fourth Democratic attempt to invoke war powers constraints, voting 52, 47 on Wednesday to table the measure. But with the U.S.-led campaign in Iran now past its 45th day, the comfortable margin that has shielded the White House may be narrowing, not because Democrats found new votes, but because Republicans who backed the president are starting to ask harder questions.

Collins, speaking at the Semafor World Economy summit, laid down a clear marker:

"I have said from the very beginning that if the military hostilities in Iran continue to that 60th day, then I believe the War Powers Act is implemented, and the president would need congressional authorization to continue the war in Iran."

She went further, telling Semafor that she had "always wanted this operation to be brief but successful" and that it was "very likely" she would vote against authorizing further hostilities if the deadline arrives without a resolution.

Tillis raises strategic doubts

Tillis, who is not running for reelection and therefore faces no primary pressure to stay in line, offered a blunter assessment in an exclusive NBC News interview. He called it "difficult" to win his support for extending the conflict past 60 days and pointed to a gap in the administration's public case.

"What's concerning me now is we're coming up on the 45-day mark. Sixty days is important with respect to the War Powers Resolution, and I'm not quite clear what the strategic objectives are."

That last line, "not quite clear what the strategic objectives are", is the kind of sentence that should focus minds at the Pentagon and the West Wing. Tillis is no dove. He voted to block every Democratic war powers resolution so far. When a loyal ally says he cannot identify the mission's goals approaching the halfway mark of the legal window, the administration has a communications problem at minimum.

Tillis did leave himself room, saying he was "not a no" on additional military funding but would need specifics. The distinction matters. He is not grandstanding against the president. He is asking for a plan, a reasonable request from a senator whose constitutional duty includes authorizing the use of force.

The War Powers Resolution and the 60-day clock

The War Powers Resolution, enacted in 1973, limits the president's authority to wage war abroad without the consent of Congress. It requires the commander-in-chief to notify lawmakers within 48 hours of military action and bars armed forces from remaining engaged longer than 60 days without congressional approval.

The U.S. campaign in Iran began on February 28 with joint U.S.-Israel strikes against Iranian leadership, military, and nuclear targets. That puts the 60-day mark somewhere around late April, just days away. House and Senate Democrats have forced several war powers votes since the campaign started, each time falling short as Republicans held together to reject the measures.

Wednesday's vote was the latest example. Sen. Rand Paul of Kentucky was the lone Republican to side with Democrats, while Sen. John Fetterman of Pennsylvania crossed the aisle to vote with the GOP, a pattern that has repeated itself on several high-profile Senate votes this session.

But the math changes if Collins and Tillis flip. With a 52, 47 majority already thin enough that a single Republican defection forced the White House to rely on Fetterman, losing two more GOP votes could put the president's war authority in genuine jeopardy.

Murkowski moves behind the scenes

Sen. Lisa Murkowski of Alaska adds another layer. She has been working with other Senate Republicans on a resolution that would formally authorize military force against Iran beyond 60 days, a move that implicitly concedes Congress needs to weigh in. Murkowski reportedly wants that authorization in place before agreeing to the president's request for a boost in military funding.

That approach is worth watching. Rather than simply blocking the president, Murkowski is trying to channel the constitutional process: authorize the mission, define its scope, then fund it. It is the kind of deliberate institutional maneuvering that has defined recent Senate GOP strategy on the Iran question, block premature Democratic resolutions while quietly building a framework for legitimate oversight.

Trump's message from Las Vegas

President Trump, speaking Thursday in Las Vegas, projected confidence. The Associated Press reported his remarks:

"I will say the war in Iran is going along swimmingly. It should be ending pretty soon."

The optimism is welcome if it reflects ground truth. But "pretty soon" is not a timeline, and "swimmingly" is not a strategic objective. Tillis's complaint, that he cannot identify clear goals, suggests that at least some Senate Republicans need more than reassurance. They need a briefing, a defined endstate, and a credible path to conclusion before they will extend the legal authority the president currently operates under.

None of this means the administration is in crisis. Collins and Tillis have not voted against the president yet. They have signaled conditions, not opposition. The distinction is important. Collins has shown repeatedly this session that she will work with Republican leadership when the case is made, but she expects the case to be made.

The real question Congress must answer

The War Powers Resolution exists for a reason. It was written after Vietnam to prevent open-ended military commitments that drift beyond their original purpose without democratic accountability. Conservatives who believe in constitutional order should welcome, not resent, senators who take the 60-day clock seriously.

The president has broad authority as commander-in-chief. But that authority is not unlimited, and the founders designed a system in which Congress holds the power to declare war. If the Iran campaign is succeeding, the administration should have no trouble making the case to Congress. If the objectives are unclear even to supportive Republican senators 45 days in, that is a problem worth fixing, not papering over with party-line votes.

Democrats, for their part, have tried to exploit the war powers issue for political advantage since day one, forcing repeated votes designed less to assert congressional authority than to embarrass the president. That pattern of reflexive opposition has made it easy for Republicans to dismiss every resolution as partisan theater. But the approaching deadline changes the calculus. When the 60-day mark arrives, the question stops being about Democratic messaging and starts being about the Constitution.

Tillis put it plainly: sixty days matters. Collins drew a bright line. Murkowski is drafting an authorization. These are not acts of rebellion. They are acts of governance, the Senate doing what the Senate is supposed to do.

The White House has roughly two weeks to bring its own party along. That means clear objectives, a credible timeline, and a willingness to submit to the process the Constitution requires. Senate Republicans have shown they can unify when leadership gives them something concrete to rally behind. The question now is whether the administration will provide it, or assume loyalty alone will carry the vote.

A president who wins the argument in Congress comes out stronger than one who avoids it. That has always been true, and it is especially true when the stakes are measured in American lives and the credibility of American power abroad.