July 25 (Reuters) - A federal appeals court on Saturday declined to allow U.S. President Donald Trump's administration to implement in 23 states an executive order he signed that aims to tighten rules ‌for mail-in voting ahead of November elections that will decide control of Congress.

The Boston-based 1st U.S. Circuit Court of Appeals rejected the administration's request to lift an injunction several Democratic-led states secured on June 25 from a lower-court judge who concluded that key parts of the Republican president's order were unconstitutional.

(Reporting by Lisa Richwine in Los Angeles)