In a significant rebuke to the administration, the Republican-led U.S. Senate voted Tuesday to approve legislation aimed at halting American military involvement in Iran, according to Reuters.

The practical consequences of the measure remain unclear, however, as President Donald Trump’s administration continues efforts to finalize a peace agreement with Tehran.

The resolution passed the Senate by a narrow 50-48 margin after previously winning approval in the House of Representatives earlier this month.

While the vote largely followed partisan lines, four Republican senators broke with their party to support the measure alongside nearly all Democrats. Two Republican lawmakers did not participate in the vote.

Under the resolution, the president would be directed to remove U.S. forces from ongoing hostilities involving Iran. Despite its passage, many observers view the measure as largely symbolic and unlikely to alter administration policy.

Because the legislation was introduced pursuant to the War Powers Act of 1973, it does not require presidential approval and therefore will not be sent to Trump for his signature.

The White House has already dismissed the effort, maintaining that Congress lacks the authority to impose such restrictions on the administration through this mechanism.

Administration officials argue that the resolution is unconstitutional and carries no binding legal force over the president’s conduct of military and foreign affairs.