Rep. Brian Fitzpatrick (R-PA), a moderate Republican and co-chair of the House Problem Solvers Caucus, introduced a war powers resolution on Thursday that aims to enforce the deadlines for the war in Iran laid out in the 1973 War Powers Act.

Fitzpatrick is the first Republican — other than isolationist Rep. Thomas Massie (R-KY) — to introduce legislation that would constrain the administration’s ability to act in Iran. The move is a signal that GOP support for the effort could begin to erode if the administration disregards legal limitations on the length of its operation in Iran.

The War Powers Act limits any military operation initiated unilaterally by the executive branch to 60 days, with an additional 30-day drawdown period, unless the operations are subsequently authorized by Congress. The 60-day period will expire at the end of April.

“The War Powers Act of 1973 is the law of the land,” Fitzpatrick said. “This consistent standard must be applied to all past, current, and future administrations when it comes to military hostilities abroad. … This is the law that has applied to past administrations, and it is the law that will apply to current and future administrations. This is the law and, until it is changed, it will be consistently applied and consistently enforced across all administrations and all conflicts.”

Other Republicans, including moderates, have also indicated that they would be uncomfortable with or unable to support any military operations in Iran past the 60-day deadline without additional congressional authorization — though some have said they would support such an authorization.

Yet, others have argued that the limitations in the War Powers Act are not legally binding and say Republicans on the Hill will disregard them.

Running in a highly competitive district, Fitzpatrick’s move could also be a sign of discomfort with the continued war effort among swing-district Republicans ahead of the midterm elections.