The Republican National Convention had a whole bunch of federal employees participating in the proceedings. Secretary of State Mike Pompeo, White House Press Secretary Kayleigh McEnany, and dozens of other lower-level workers all took part in the celebration of Donald Trump's nomination for re-election. Trump's speech on Thursday took place on the South Lawn of the White House — the first time the building had been used for such a purpose. To cap it all off, there was a fireworks show on the National Mall (which is public land), displaying Trump campaign slogans.
This is a straightforward violation of the Hatch Act, which limits how federal employees (not including the president and vice president) can participate in partisan election campaigns. They cannot use their "official authority or influence for the purpose of interfering with or affecting the result of an election," or "engage in political activity" while on duty, on federal property, wearing a federal uniform, and so on.
Now, one can argue with some justice that the Hatch Act is somewhat ridiculous, at least for top-level Cabinet officials, because they are inherently political. But it is the law, and as Charlie Savage writes at The New York Times, previous administrations have always tried to at least follow the letter of the law. The Trump administration is doing no such thing — instead it is flagrantly disobeying it in full view of everyone, and scoffing at critics. "Nobody outside of the Beltway really cares," White House Chief of Staff Mark Meadows told Politico about the law. (Naturally, when the president was a Democrat, Meadows espoused the exact opposite opinion.) Even if a Cabinet official is inherently political, the point of the Hatch Act is to prevent the president from leveraging his power over the federal bureaucracy to entrench himself in power. That is plainly what Trump is trying to do.