A federal judge late Sunday ordered that the U.S. Postal Service not implement President Donald Trump’s executive order limiting mail balloting, adding another obstacle to the administration’s effort to rewrite election rules as the Supreme Court is poised to weigh in on the matter.

US District Judge Carl J. Nichols in Washington, D.C., issued a preliminary injunction blocking the rule, which was issued on August 21. Nichols stated that plaintiffs had demonstrated that, absent an injunction, there is an increased risk that a significant number of otherwise appropriate absentee or mail-in ballots will ultimately not be counted in the upcoming elections. He added, "The public has a strong interest in ensuring that doesn’t happen."

This ruling follows a similar order by US District Court Judge Indira Talwani in Boston, who previously prohibited the Postal Service from enforcing its new rule on mail voting before this year’s midterm elections. The Supreme Court is already considering the administration’s appeal of Talwani’s order.

Nichols had previously refused to issue an injunction in May, ruling that the lawsuit seeking one was filed too early. The high court had cited similar reasoning when it lifted Talwani’s earlier freeze late last month. However, with the administration issuing its rule to advance Trump’s plan, plaintiffs in both Boston and Washington refiled their lawsuits.

Talwani was nominated by former President Barack Obama, and Nichols was nominated by Trump.

The new Postal Service regulations stem from an executive order Trump issued earlier this year. Election officials have stated it would be impossible to implement the changes so close to a general election. The regulations would require pre-approval from the Postal Service for all ballot envelope designs and mandate that states upload the identities of ballot recipients into a still-inactive online portal.

Mail ballots are already being sent out in at least three states—Alabama, North Carolina, and Wisconsin—with more states preparing to distribute them this week.

A whistleblower report to Congress warned that millions of people could be disenfranchised if the rule were allowed to take effect for the midterms. The union representing U.S. Postal Service workers has also pushed back against the executive order, stating that verifying voter eligibility is not the job of postal workers.

Mail balloting has been a frequent target for Trump, who has falsely claimed it was responsible for his 2020 election loss and is a pathway to fraud, despite his own use of the voting method.