“Using the Park Service for a blatantly political speech, such as accepting a nomination for a political role, presents a major hazard of violating the Hatch Act, which forbids any federal employee other than the president or vice president from engaging in political activity at their workplace during their hours of duty. Therefore, if any Park Service employee significantly aids or appears in the speech — such as being a background prop for Pence — they might be at risk of violating the federal law.
In a speech that surely will be watched by many millions of Americans, it would be grossly political to directly or indirectly imply that Park Service staff are supporting Pence’s renomination.”