The leaders of 23 Democratic-run US states have sued to block new mail-in voting restrictions that were issued in an executive order signed by US President Donald Trump earlier this week.
The lawsuit argues that the president does not have the constitutional right to interfere with elections, which are run by state governments.
The new rules "transgress Plaintiff States' constitutional power to prescribe the time, place, and manner of federal elections" and attempt to "amend and dictate election law by fiat based on the President's whims", according to the lawsuit.
The US Constitution gives oversight of federal elections to the states, while Congress has the ability to make changes.
Trump has promoted claims without evidence of widespread voter fraud through mail-in voting. He said he recently voted by mail in Florida because he is the US president. His son and wife have also voted by mail in recent elections.
