A federal appeals court has upheld a ruling that blocks President Donald Trump’s executive order to create a federal list of eligible voters and restrict the delivery of mail ballots to people included on the list in nearly half of US states.

A panel of judges from the 1st US Circuit Court of Appeals on Saturday rejected the Trump administration’s effort to implement the mail-in voting restrictions in 23 states that had challenged the order ahead of November’s midterm elections.

Trump issued the executive order in March directing the head of US Citizenship and Immigration Services and the commissioner of the Social Security Administration to create a “state citizenship list” of eligible voters. The order also directed the US Postal Service to deliver mail ballots only to people on the list.

Trump has described the proposed changes as safeguards to prevent non-US citizens from voting. However, state election officials argued that the measures could be abused and create confusion in the election process.

Democratic officials from 23 states and the District of Columbia challenged the order in a lawsuit filed in US District Court in Boston.

They argued that Trump’s order was unconstitutional because states and Congress, rather than the president, have the authority to establish election rules.

US District Court Judge Indira Talwani, who was nominated by Democratic President Barack Obama, agreed with the challengers and blocked implementation of Trump’s order for the Nov. 3 elections, but only in the states that filed the lawsuit.

The Justice Department said in an emailed statement Sunday that it is “reviewing all options” for its next legal steps and remains confident that Trump’s executive order will ultimately be upheld.