A court has just told the President of the United States he is a tenant. His ballroom is due to open four months before he has to move out.

A federal appeals court has told the President of the United States that he rents.

"Each President is a temporary tenant, not the owner, of the White House and its Executive Residence," the DC Circuit ruled on Friday, halting construction of Donald Trump's ballroom.

"The President has no - and claims no - constitutionally assigned authority over that property, which is designed and maintained for the use of all Presidents, current and future, and for the American people."

The trial judge who first blocked the work, George W. Bush appointee Richard Leon, had put it more bluntly.

"The President of the United States is the steward of the White House for future generations of First Families," he wrote. "He is not, however, the owner!"

The 2-1 ruling upheld an injunction won by the National Trust for Historic Preservation. Only Congress can authorise reshaping the White House, the majority found, and a massive ballroom "is for Congress to decide and is not a matter for executive self-help".

The court stayed its own order for 14 days so the administration can appeal to the Supreme Court. Mr Trump said he would.

He called the decision "horrendous, politically motivated, and unlawful" and described the structure on Truth Social as a "military centre", saying it was "a National Security Threat at the highest level" to stop it.

The East Wing, built in 1902, was demolished last year to clear the site. The replacement is 8,360 square metres and seats 999. The East Room it supplements holds 200.

The price has moved four times. The White House first said $200 million, then $300 million, then $400 million. An internal contractor estimate obtained by the Washington Post in June put it at $600 million, with roughly half coming from public money - $155 million from the Secret Service, $149 million from the White House Military Office.

Mr Trump had promised it would cost taxpayers "not one dime".

Then there is the question nobody is asking.

In May he said the project was ahead of schedule and would open around September 2028. His term ends on 20 January 2029.

That is a room that has cost $600 million and taken three years, available for four months of state dinners, and then handed to whoever wins.

Unless he stays.

Mr Trump has raised a third term more than a dozen times. He wore a "Trump 2028" cap to the White House Correspondents' Dinner in July and said the third time would be better, then said he was joking. He has also said plainly that the 22nd Amendment means "I'm not allowed to run". Speaker Mike Johnson says there is "no path".

The court has now told him the house is not his. The calendar says the ballroom is not either.