WASHINGTON — President Trump’s military parade will not come cheap.

Mick Mulvaney, the White House budget director, estimated on Wednesday that the public display of America’s military might that Mr. Trump has called for could cost between $10 million and $30 million, and said the government would have to come up with a way to cover the cost.

Funding for the parade was not included in the White House’s 2019 budget request, which was released on Monday, because it was a relatively new idea, Mr. Mulvaney said at a House Budget Committee hearing on Wednesday. He explained that the final cost would be determined by the size, scope and length of the parade.

“We will continue to work with you folks if we decide to continue forward with this initiative,” Mr. Mulvaney said. “Of course, you’d have to appropriate funds for it or we would have to find funds that we’ve already appropriated.”

Stan Collender, a former staff member on the House and Senate budget committees, said that the funding for the parade could be found without a formal budget request by using existing money already in the Department of Defense budget or possibly from the Department of Homeland Security or the National Park Service.