Boston, Massachusetts - A federal judge on Thursday temporarily blocked President Donald Trump's order tightening mail-in voting rules just over two months before the midterm elections.

The rules were a "likely unconstitutional regulation for which compliance is practically impossible as to the 2026 midterm elections," Judge Indira Talwani wrote.

She said the measures could not realistically be implemented because the first states are due to begin sending out mail ballots as early as next week.

The new rules would give the US Postal Service a central role in overseeing mail voting. States would have to submit the design of their mail-ballot envelopes for approval, while the USPS would only deliver voting materials to people listed on voter rolls provided by the states.

Republicans have defended the measures as necessary to prevent alleged election fraud, while critics say Trump is seeking to make voting by mail more difficult.

Democratic voters have generally been more likely than Republicans to vote by mail.

The November 3 midterms will decide all seats in the House of Representatives and about a third of the Senate.

With Republicans holding narrow majorities in both chambers, control of Congress could hinge on only a handful of races. Losing either chamber would make it significantly harder for Trump to push through his political agenda.

Talwani had previously blocked the rules, but the Supreme Court lifted that order on Monday on procedural grounds rather than ruling on the legality of the measures.

The Trump administration is expected to challenge the latest order.