The Postal Service proposed a new rule pushing states to turn over their mail-in and absentee voter rolls to the agency, a move in line with President Donald Trump’s March executive order tightening regulations on mail-in voting in federal elections.

Since the start of his second administration, Trump has made election integrity and security a central issue, signing multiple executive orders to require proof of citizenship and crack down on mail-in voting fraud, essentially establishing a national voter verification system. His efforts have run into several legal hurdles, with judges ruling against requirements for proof of citizenship as Trump’s appeal pends, and several Democratic states sue over the mail-in voting order.

As the battle plays out in court, the USPS followed the White House’s order that the agency propose a rule outlining a method for each state and the postal carrier to agree on a list of voters eligible to receive mail-in and absentee ballots, and how mail-in ballots should be packaged. The agency’s proposed rule would create a “Mail-In and Absentee Participation List” in line with Trump’s request.

The state would first submit to the USPS a list of voters who are submitting mail-in ballots for that election, along with each voter’s corresponding personalized barcode on their ballots. Then, the USPS would return a final “Mail-In and Absentee Participation List” to each state’s chief election official to finalize the names of all enrolled voters in the state and the barcodes associated with their ballots.

Voters who receive mail-in or absentee ballots must be included on this final “Mail-In and Absentee Participation List,” marking a significant change in the rules and regulations for mail-in and absentee voting.

“This provision will help determine adherence to federal law and facilitate law enforcement efforts,” the rule proposal reads. “For example, the provided lists will evidence how many ballots have been mailed, and allow law enforcement officials to compare the total number of mailed ballots to the total number of received ballots to detect potential issues meriting further investigation.”

The USPS issued the proposed rule on May 29, one day after Trump-nominated District Judge Carl J. Nichols in the District of Columbia denied Democrats’ injunction request against the mail-in voting executive order from March. Nichols said the plaintiffs failed to adequately substantiate their claims of “imminent and irreparable harm” that the executive order would cause them.

The Democratic plaintiffs appealed the ruling and, as the appeal pends, the USPS proposal remains in legal limbo.