President Donald Trump’s executive order seeking broad changes to how elections are run in the U.S. is vast in scope and holds the potential to reorder the voting landscape across the country, even as it faces almost certain litigation.

Pennsylvania election officials and experts said Wednesday that it’s highly unlikely a sweeping executive order from President Donald Trump seeking to require proof of citizenship for voters and altering rules for administering elections will take full effect.

The order lays out identification requirements and prohibits the counting of absentee or mail-in ballots received after Election Day.