The Supreme Court on Monday blocked a Trump administration plan that would have required the U.S. Postal Service to screen mail-in ballots through new verification steps ahead of the midterm elections.

In a brief unsigned order, the court declined to lift a lower-court injunction that halted the rules. The majority concluded the administration was unlikely to succeed on the merits and that the balance of equities did not favor immediate implementation. Justice Brett Kavanaugh filed a concurrence noting that state and local officials lacked sufficient time to reasonably adopt the changes before the election. Justices Samuel Alito and Clarence Thomas dissented.

The plan called for states to submit lists of voters approved to receive mail ballots. The Postal Service would then deliver ballots only to those on the lists and require approved envelopes featuring unique barcodes for each voter. Administration officials described the measures as necessary safeguards to verify eligibility and reduce opportunities for fraud in mail voting.

Lower courts had previously ruled that rolling out the requirements so close to the election risked widespread disruption. Several states had already begun mailing ballots, and officials warned that sudden changes could delay delivery or leave voters without access to requested ballots.

President Trump has long advocated stricter controls on mail-in voting, citing concerns over chain-of-custody issues and potential abuse. The administration had argued the Postal Service possessed authority under federal statutes to set delivery standards for election mail.

The ruling leaves the existing system in place for the November contests, when control of Congress hangs in the balance. Legal challenges to the underlying policy are expected to continue in lower courts for future election cycles.