Federal agencies and the Ultimate Fighting Championship have spent more than $60 million preparing for Sunday's UFC event on the White House South Lawn, according to court filings related to a legal challenge over the event.

President Donald Trump and his administration are hosting the event.

The event, to celebrate America's 250th anniversary, falls on Trump's birthday, and has required the construction of a UFC octagon on White House grounds.

There have been extensive security preparations, food service operations, and a workforce of up to 900 people who have been on-site since May 20.

The Executive Office of the President, the U.S. Secret Service, the U.S. Park Police, the Department of the Interior, the National Park Service, the Department of Homeland Security, and the Federal Aviation Administration are among the agencies involved in coordinating the event.

"In preparation, well over $60 million and tens of thousands of hours of labor have been expended," the government said in a court filing Tuesday. "More than 4,000 spectators are expected to attend on the South Lawn, including more than 1,000 members of our armed services, and more than 120,000 visitors are expected to watch from the nearby Ellipse after winning free tickets in a lottery."

"Many of the event's attendees will visit from outside the capital region, and have already invested personal resources in lodging, air transportation and other arrangements," the filing continues. "Fourteen world-class athletes, who have been training for months, have traveled from all over the world to compete (including for two world championships)."

The filing says UFC parent company TKO Group Holdings is funding the event despite expecting it to operate at a loss.

"We will not be making money on America's 250th anniversary," Mark Shapiro, president and chief operating officer of TKO, told The Hollywood Reporter. "This is an investment for the long term. This is about earned media."

"We see this once-in-a-lifetime stage as a strategic investment to drive subscriber acquisition at Paramount+, massive audience sampling for the UFC overall and Super Bowl-like earned media across the globe," he added.

The event has also sparked legal challenges from critics seeking to block it.

One lawsuit alleges the arrangement is "deeply corrupt" and claims major corporations are seeking a prominent presence at the White House.

According to the complaint, sponsors "are clambering over each other to see their brands plastered adjacent to the Executive Residence and Reflecting Pool."

The lawsuit further claims: "And the UFC's broadcast partner, Paramount Skydance — which is run by two other Trump allies, Larry and David Ellison — has decided that no American will be able to take in this 'celebration of America' without first paying $8.99 plus tax for a Paramount Plus streaming subscription."

Plaintiffs also raised questions about Trump's previously disclosed purchase of TKO stock before the event.

Amid criticism from opponents, the Trump administration is expected to sign a memorandum of understanding with UFC on Thursday establishing a public-private partnership tied to the event.