1 of 6 | President Donald Trump speaks to the press about the new East Wing next to the construction site at the White House in Washington, D.C., on Tuesday. Photo by Samuel Corum/UPI | License Photo

May 20 (UPI) -- President Donald Trump's plan to build a new White House ballroom remains in the air as preservation advocates urge for Congressional approval and oversight.

Calls for construction of a 90,000 square foot ballroom built on the East Wing of the White House ramped up after an alleged assassination attempt during the White House Correspondents' Dinner on April 25. How much the ballroom would cost and how it would be funded remain in question.

The National Trust for Historic Preservation filed a lawsuit in December against the Trump administration over the ongoing construction project. It has asked that the project be stopped until the administration goes through the legally mandated review process with a public comment period and complies with relevant laws.

U.S. District Judge Richard Leon ordered above-ground construction to halt on April 1. The Circuit Court of Appeals is scheduled for a hearing in the case on June 5.