The administration's efforts sparked a legal battle involving the League of Women Voters and a coalition of states challenging the federal government's authority to impose the changes.

Under the USPS final rule, state and local election officials would have been required to meet new ballot-envelope design standards, submit the designs to the Postal Service for approval, and upload voter information into a USPS-operated electronic portal.

Critically, the rule provided that USPS would not mail ballots when officials failed to obtain required envelope approval, upload voter information, or include required barcodes. Talwani found the states and organizations challenging the rule were likely to succeed on several of their claims.

The judge said the USPS likely lacked the authority to issue the rule and found challengers were likely to succeed in arguing its requirements were unconstitutional.

Talwani wrote: "The Constitution charges the States with election administration."

The court also determined states could face "irreparable harm" attempting to comply with the requirements with the November midterms little more than two months away.

According to the order, most of the states involved have already ordered their mail ballots, while some are legally required to begin sending them to eligible voters as early as next week.

Talwani said officials would have insufficient time to redesign ballots, obtain USPS approval, order new materials, update election systems, train workers, and upload voter information before the election.

She warned the threat to voters was "grave," particularly for people who rely on mail voting because of age, disability, or where they live.

In another passage, Talwani took aim at the justification behind the rule.

She wrote: "The record continues to lack any evidence regarding fraudulent absentee or mail-in voting."