President Trump on Wednesday defended the cost of his "Salute to America" event on Independence Day amid mounting criticism from Democrats that the spectacle will amount to a campaign rally at taxpayers' expense.

The president claimed the cost of the event "will be very little compared to what it is worth."

"We own the planes, we have the pilots, the airport is right next door (Andrews), all we need is the fuel," Trump tweeted. "We own the tanks and all. Fireworks are donated by two of the greats. Nice!"

It's unclear what Trump is referring to by the event's worth, as entry to the National Mall for the event is free.

Trump's tweet follows a Washington Post report on Tuesday night that the National Park Service will divert $2.5 million in entrance fees intended to improve parks nationwide to cover costs for Trump's Fourth of July event.

The Interior and Defense departments have not provided specific costs for the event, but it is expected to come with an exorbitant price tag.

Trump's presence will lead to added security and overtime costs, and the use of tanks and military aircraft will add hundreds of thousands of dollars to the tab. Democrats and local officials have voiced concerns that the tanks in particular will damage infrastructure, leading to additional costs.

Democrats have pressed the Department of the Interior for specifics on the expected cost, but have said they've yet to receive a response.

"It is unacceptable that the Interior Department is failing to inform Congress about how it plans to spend taxpayer money to fund the president's lavish July 4th plans, which reportedly include special access to the National Mall for the politically connected," Sen. Tom Udall (D-N.M.) said in a statement Tuesday.

"The American people deserve to know how much of their money the president is spending to turn their July 4th celebration into a de facto campaign rally," he added.