A federal appeals court ordered Friday that the construction of the proposed White House ballroom must get congressional approval to proceed, dealing President Donald Trump another setback in his ambitious project for the executive mansion.

The U.S. Court of Appeals for the D.C. Circuit ruled 2-1 that construction must stop on the extensive renovation of the East Wing, which includes a new ballroom, because Congress has control over how the White House may be changed, not the executive branch, despite it being the executive mansion. The two judges sided with the National Trust for Historic Preservation, a preservationist group, which sued the Trump administration late last year when construction on the ballroom began.