A federal judge in Washington ordered the Trump administration on Tuesday to halt construction of a proposed $400 million White House ballroom, ruling that President Donald Trump lacks the authority to proceed without congressional approval.

U.S. District Judge Richard J. Leon, a George W. Bush appointee, granted a preliminary injunction sought by the National Trust for Historic Preservation. The order pauses work on the 90,000-square-foot ballroom planned for the site of the demolished East Wing, effective in 14 days to allow for a possible appeal. Work necessary for White House safety and security remains exempt.

In a 35-page opinion punctuated by 18 exclamation points, Leon wrote, "Unless and until Congress blesses this project through statutory authorization, construction has to stop!" He emphasized that "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!"

The project, announced by the White House in July 2025, aims to build a grand ballroom capable of hosting 999 guests. Funded entirely by private donors at no cost to taxpayers, construction followed the East Wing's demolition in October 2025. Above-ground work was set to begin next month after crews recently replaced colonnade flooring.

The National Trust sued in December 2025, arguing the administration bypassed required reviews and congressional oversight for altering federal property. Leon previously denied injunction requests in December and February but allowed the complaint to be amended. During a March 17 hearing, he expressed skepticism toward the Justice Department's shifting defenses.

The Trump administration defended the project as a necessary modernization for security and operations. A Trump-appointed Commission of Fine Arts panel approved the design in February. The National Capital Planning Commission is slated to vote on the plans Thursday.

President Trump, who yesterday touted the ballroom as "ahead of schedule and under budget" while unveiling revised renderings aboard Air Force One, responded on Truth Social. He called the National Trust a "Radical Left Group of Lunatics whose funding was stopped by Congress in 2005" and questioned the suit over a privately funded endeavor.

Carol Quillen, president of the National Trust, hailed the ruling as "a win for the American people on a project that forever impacts one of the most beloved and iconic places in our nation." The White House deferred comment to Trump's post.

Leon noted Congress could still authorize the project, suggesting it was "not too late." The administration may appeal to the D.C. Circuit.