Adam Liptak and Peter Baker at the Times spare a thought for Trump’s lawyers.

In a series of Twitter posts Monday that continued into the evening, Mr. Trump may have irretrievably undermined his lawyers’ efforts to persuade the Supreme Court to reinstate his executive order limiting travel from six predominantly Muslim countries, according to legal experts.

Saying he preferred “the original Travel Ban, not the watered down, politically correct version” he had issued in March, Mr. Trump attacked both the Justice Department and the federal courts. He also contradicted his own aides, who have suggested he was causing a pause in travel, by calling the order “what we need and what it is, a TRAVEL BAN!” He said it would be imposed on “certain DANGEROUS countries” and suggested that anything short of a ban “won’t help us protect our people!”

He did the thing lawyers want their clients not to do: he blabbed. The first thing lawyers tell their clients is SAY NOTHING. Donnie doesn’t do Say Nothing.

Still, some administration supporters said the court should not consider the tweets. While looking beyond the letter of the order might be appropriate in domestic policy, the president has a freer hand in foreign policy, said David B. Rivkin Jr., a lawyer in the administrations of Ronald Reagan and George Bush. “As a constitutional matter, as a legal matter, it should make absolutely no difference,” he said of the president’s extracurricular messaging.

Last week, lawyers in the solicitor general’s office filed polished briefs in the Supreme Court. They urged the justices to ignore incendiary statements from Mr. Trump during the presidential campaign, including a call for a “Muslim ban.” The court should focus instead on the text of the revised executive order and statements from Mr. Trump after he had taken the inaugural oath to “preserve, protect and defend the Constitution,” the briefs said.

Mr. Trump, his lawyers said, was now a changed man, alert to the burdens and responsibilities of his office.

“Taking that oath marks a profound transition from private life to the nation’s highest public office, and manifests the singular responsibility and independent authority to protect the welfare of the nation that the Constitution reposes in the president,” they wrote.

Ah no. No no. No no no no. That’s what you’d expect but it’s absolutely not what happened. That’s why we’re all so amazed. It never stops being amazing how completely he has not changed, how entirely the huge responsibilities of the office have not forced him to grow up.

On Twitter early Monday, though, Mr. Trump appeared to say that the latest executive order was of a piece with the earlier one, issued in January, and with his longstanding positions.

In calling the revised order “politically correct,” Mr. Trump suggested that his goal throughout had been to exclude travelers based on religion. And in calling the revised order “watered down,” he made it harder for his lawyers to argue that it was a clean break from the earlier one, which had mentioned religion.

Other than that, they were very helpful.

Mr. Trump’s adversaries certainly welcomed his tweets.

“It just adds to the mountain of already existing evidence that the government has had to ask the court over and over to ignore,” said Omar Jadwat, a lawyer with the American Civil Liberties Union, which represents people and groups challenging the law. “Blinding the courts to a reality that everyone else is aware of is never an attractive position, but is especially problematic when you have to ignore in real time what’s being said by the president of the United States.”

Neal K. Katyal, who represents Hawaii in a separate challenge to the order, said there was a yawning gap between Mr. Trump’s tweets and his lawyers’ filings.

“The president’s statements, before, during and after his inauguration, continually demonstrate what his so-called travel ban is really about,” Mr. Katyal said. “It’s not surprising his story and his tweets don’t match up with what the solicitor general has been trying to say in court.”