The decision replaces a temporary order issued earlier this month.

A divided United States Supreme Court has allowed the White House to continue construction on a $400m ballroom project as lawsuits play out, a win for President Donald Trump as he flexes unprecedented executive power and remakes the capital in his image.

The apparent 5-4 decision replaces a temporary order that allowed construction earlier this month, shortly before a court-ordered halt would have gone into effect.

The temporary order was signed by US Chief Justice John Roberts, assigned to handle appeals from the capital. But he publicly disagreed with the latest decision, writing a strong dissent that referenced historical figures and calling the project “likely unlawful” because it has not been approved by Congress.

“Today’s decision is no victory for the separation of powers.” Roberts wrote. The court’s three liberal-leaning justices agreed.

The majority did not decide the legality of the project, but found that a preservation group likely did not have the legal right to challenge it. The unsigned opinion also cited the national security concerns that the government says the project would address.

The lawsuit will return to lower courts, but documents say that key portions of the project could be complete within months – a quick timeline compared with a typical legal case.

The Trump administration asked the justices to intervene after federal courts found the project must halt because it did not have congressional approval.

The lawsuit from the National Trust for Historic Preservation argued that Trump has no unilateral authority to undertake the work, which has included demolishing the East Wing. The group’s lawyers accused the White House of trying to “outrun the courts” by accelerating construction.

In lower courts, the Trump administration has argued that the president has total authority to renovate the White House and other federal buildings. Government lawyers said the ballroom project must be completed due to national security concerns, though those were not an initial focus when Trump announced the work and said it would be funded by private donations.

“This case involves an extraordinary ⁠and unlawful injunction that will halt the ongoing construction of the integrated military complex, including a totally secure ballroom space, at the East Wing of the White House, which is vitally required by national security,” the lawyers wrote in an August 14 filing.

The administration has said that crews are working 20 hours a day on the planned 8,400 square metre (90,000 square foot) ballroom. The framework is expected to be completed in November, and much of the facade done by April, with full completion slated for August 2028, according to court documents.

US District Judge Richard Leon ordered a stop to aboveground construction of the planned ballroom in April, though the order would allow work on bunkers and military installations below ground to continue. Leon was nominated by former President George W Bush, a Republican.

The ruling was suspended but later upheld by a divided appeals court panel. Two judges appointed by Democratic presidents found the project was for Congress to decide and “not a matter for Executive self-help”. A third judge, appointed by Trump, found that the preservationist group that challenged the project had no legal right to sue.

Solicitor General D John Sauer also made that argument to the justices and said the decision halting the work was “extraordinary and unlawful”. He said the completion of the project was “vitally required by national security.”

The administration has scored a series of other victories on the high court’s emergency docket, though the justices have ruled against some of the president’s signature policies after fuller review.

The demolished East Wing housed the first lady’s offices and the White House movie theatre. It was originally built in 1902, during Theodore Roosevelt’s presidency, and greatly expanded in 1942, during Franklin Roosevelt’s presidency.