WASHINGTON — For months, President Donald Trump portrayed the big new ballroom that he’s building on White House grounds as a gift to the nation, courtesy of patriotic private donors.

“And by the way, no government funds,” Trump told reporters in the Oval Office last November.

“These are all private individuals that put up a lot of money to build the ballroom,” he added. "Not one penny is being used from the federal government."

But the gleaming 90,000 square-foot space that he repeatedly said would cost the public nothing may ultimately leave taxpayers on the hook for $1 billion, due to new security enhancements that are tied to the project.

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Senate Judiciary Committee Chairman Chuck Grassley, R-Iowa, has released a long-term immigration and border patrol funding bill that includes $1 billion earmarked for security improvements accompanying the overall ballroom project.

The legislation states that the money is earmarked “for the purposes of security adjustments and upgrades, including within the perimeter fence of the White House Compound to support enhancements by the United States Secret Service relating to the East Wing Modernization Project, including above-ground and below-ground security features.”

The language is part of a Republican-only "reconciliation" bill the party plans to pass this year. The overall package is a major priority for GOP leadership, as well as the president. Still, some Republicans expressed skepticism about taxpayers contributing to the ballroom just last week.

In a prepared statement, a White House spokesman praised the Republican-led spending proposal.

“Congress has rightly recognized the need for these funds," said Davis Ingle, a White House spokesman. "Due in part to the recent assassination attempt on President Trump at the White House Correspondents’ Dinner, the proposal would provide the United States Secret Service with the resources they need to fully and completely harden the White House complex, in addition to the many other critical missions for the USSS."

Senate Democrats hope to derail the $1 billion proposal. They plan to force a vote to try to strip the provision out of the bill when it comes to the Senate floor later this month.

“Just flagging that now everyone gets an up or down vote on the ballroom!” Sen. Brian Schatz, D-Hawaii, said in a post on X.

When he first laid out plans for the ballroom last year, Trump emphasized that it would fulfill a need for large-scale parties at the White House at no cost to the public. Foreign leaders shouldn’t be shuttled out to the White House South Lawn for state dinners held beneath make-shift tents, Trump argued.

“This is a GIFT (ZERO taxpayer funding!) to the United States of America, of 300 to 400 Million Dollars (depending on the scope and quality of interior finishes!), for a desperately needed space," Trump wrote on his social media site in January.

He demolished the White House’s East Wing to make room for the ballroom and raised millions of dollars in corporate contributions to pay for it. (Comcast Corp., the parent company of NBCUniversal, is one of the donors.)

As construction proceeded and legal challenges arose, the White House began to emphasize another rationale for the ballroom: safety.

In a court filing last month, the Trump administration wrote that the structure is "vital" for the president and White House's security and will be built with materials that can withstand drone attacks.

More than a ballroom, the project also includes underground medical facilities and a bomb shelter, the administration’s filings showed.

After a gunman last month stormed into the White House Correspondents’ Association Dinner, where Trump was seated at the dais in a bustling Washington, D.C., hotel, the White House renewed its argument that the ballroom is needed to ensure the president’s safety.

Opponents say that the new funding proposal suggests that Americans were misled when Trump told them the ballroom would cost them nothing.

Sen. Richard Blumenthal, D-Conn., told NBC News: “This has been a bait and switch: promising it would be privately funded and now, apparently, taxpayers will be on the hook for it.”

Sen. Chris Coons, D-Del., said in an interview: “This is tragically another example of President Trump promising one thing and doing another — of saying he was going to do something great for the American people and instead demolishing the historic East Wing without any serious consultation or public input. And now we discover the total cost is going to be well more than $1 billion.”

“And I’ve had no briefing that gives me any insight into what could possibly cost $1 billion extra dollars," Coons added.

The ballroom project faces legal challenges that threaten its continuation. One argument that plaintiffs have made is that Trump acted without congressional approval.

Next month, a federal appeals court will hear oral arguments on a challenge to U.S. District Judge Richard Leon’s order blocking the Trump administration from moving forward with construction without congressional authorization. Until a decision comes down from the appeals court — which won’t happen until mid-June at the earliest — construction both above and below ground will continue.