The blocked portion of the order would have changed the federal voter registration form to indicate proof of citizenship is required.

"Here we are again," wrote U.S. District Judge William Orrick, who blocked a similar effort during the president's first term.

The judge’s order halts the Trump administration’s efforts to push through a proof-of-citizenship mandate that Republicans have said is needed to restore public confidence in elections. Voting in federal elections by noncitizens is already illegal and can result in felony charges and deportation.