In the past, presidents went out of their way to ensure their official remarks did not veer into political territory. Copies of speeches were meticulously edited by the White House Counsel’s Office, which would flag lines that could violate the Hatch Act, a Depression-era law that prohibits federal employees from engaging in political activities while on the job.

The president is not subject to the Hatch Act but everyone who works for him is. Speechwriters and policy advisers who helped prepare those remarks, for instance, could be in violation of the act if they were crafting an overtly political speech for the president. But the Hatch Act is ultimately self-enforcing, and toothless if the president chooses to ignore warnings from White House lawyers about possible violations…

In a January report, the Government Accountability Office estimated that four trips Mr. Trump took from Washington to his Mar-a-Lago Club in Palm Beach, Fla. over a one-month period in early 2017 cost federal agencies about $13.6 million. The Defense Department and the Department of Homeland Security incurred most of those costs, which were covered by taxpayers just as Mr. Obama’s annual personal trips to Hawaii or Martha’s Vineyard, Mass., were.

Presidents have often tried to defray the travel costs by tacking on an official event on the way to a campaign rally, and passing the bill onto the government. What they did not do was effectively turn an official event into a campaign rally.