The U.S. Postmaster General stated the Postal Service will withhold mail‑in ballots in any state that does not share its voter data.
The move follows a proposed rule that asks states to disclose their mail voting lists.
If a state refuses, ballot delivery could be postponed or halted during an election.
The Postal Service says the requirement is needed to keep mail processing efficient.
Officials note the rule would give the agency the information it needs to sort and deliver ballots on time.
Critics warn the action could affect voters in tight races.