A U.S. federal appeals court ordered President Donald Trump’s administration on Friday ‌to stop construction on a $400 million ballroom on the site of the White House’s demolished East Wing, dealing the Republican leader a major setback in a case testing his presidential authority.

“Each President ⁠is a temporary tenant, not the owner, of the White House” and cannot fundamentally reshape it without congressional approval, the Washington-based U.S. Court of Appeals for the District of Columbia Circuit said in a 2-1 opinion.

The order upheld a preliminary injunction won by ‌the National Trust for Historic Preservation, which sued last year after the administration tore down the East Wing and began building a 90,000-square-foot (8,360-square-meter) ballroom without seeking authorization from Congress.

“Whether or not a massive ballroom ‌should be constructed is for Congress to decide and is not a matter for Executive self-help,” the panel’s ‌majority ⁠wrote. “Congress has not ceded unfettered authority to the Executive Branch to dramatically redesign, reshape, and reconstruct ⁠the White House — the People’s House — to fit a particular President’s desires.”

The appeals court placed its ruling on hold for 14 days to allow the Trump administration to appeal to the U.S. Supreme Court.