WASHINGTON, D.C. — U.S. District Judge Richard Leon issued an order temporarily halting construction of President Donald Trump's White House ballroom project. The ruling takes effect in 14 days to allow time for appeal.

The National Trust for Historic Preservation sued the White House over the ballroom project. The preservation group argued that the White House began construction without filing plans with the National Capital Planning Commission, did not seek an environmental assessment of the ballroom project, and declined to seek authorization from Congress for the project.

"Unless and until Congress blesses this project through statutory authorization, construction has to stop!" Leon wrote. "I have concluded that the National Trust is likely to succeed on the merits because no statute comes close to giving the President the authority he claims to have."

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

The injunction exempts construction work that is strictly necessary to ensure the safety and security of the White House. Leon was appointed by President George W. Bush.

The East Wing of the White House was demolished in October to make way for the ballroom. The White House announced the ballroom project over the summer, saying private donations, including from President himself, would pay for the planned construction of a 90,000-square-foot ballroom.

The project is expected to cost $400 million and is being funded entirely by private donors.

President Donald Trump vowed to appeal the ruling. "The National Trust for Historic Preservation sues me for a Ballroom that is under budget, ahead of schedule, being built at no cost to the Taxpayer, and will be the finest Building of its kind anywhere in the World," he wrote on his Truth Social account.

He said the current setup is inadequate to host dignitaries such as King Charles III and that a ballroom tent is not sufficient because the grass can get wet when it rains. "Doesn't make much sense, does it?" he wrote in a social media post.

"We are pleased with Judge Leon's ruling today to order a halt to any further ballroom construction until the Administration complies with the law and obtains express authorization to go forward. This is a win for the American people on a project that forever impacts one of the most beloved and iconic places in our nation," said Carol Quillen, President and CEO of the National Trust for Historic Preservation.