WASHINGTON (Reuters) - Battle tanks were seen on a train in Washington on Tuesday ahead of a July Fourth celebration highlighting U.S. military might that Democrats say President Donald Trump may turn into a re-election campaign rally.

Amid questions about the cost and tone of the event, White House officials said the Republican president will avoid politics and stick to patriotic themes in his speech in front of the Lincoln Memorial in Washington on Thursday.

Reuters photographed M1 Abrams tanks and other armored vehicles atop flat rail cars in Washington on Tuesday morning, a sign of the military firepower that will be featured, differing significantly from past annual celebrations of the 1776 Declaration of Independence.

For decades, U.S. presidents have kept a low profile during the event, which typically draws hundreds of thousands of people to Washington’s monument-lined National Mall for a concert and fireworks.

This year, Trump plans to speak at a military “Salute to America” that will feature military bands and flyovers from the U.S. Navy’s Blue Angels and Air Force One, the modified Boeing 747 that transports U.S. presidents.

The event could also feature M1 Abrams battle tanks, a B-2 bomber, F-35 and F-22 fighter jets, and the Marine One helicopter that transports the president, the Pentagon said. Air traffic at nearby Ronald Reagan National Airport will be suspended during the flyovers and the fireworks, according to the Federal Aviation Administration.

The antiwar group Code Pink said it had secured a permit to bring a “Baby Trump” blimp, depicting the president in diapers, to a protest in the Mall during his speech. The permit does not allow the balloon to be filled with helium so it can float.

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Democrats in Congress have questioned whether Trump will turn a patriotic celebration into a taxpayer-funded campaign rally.

“That’s absolutely ridiculous. This is all about a salute to America. The president is not going to get political,” White House spokesman Hogan Gidley said on Fox Business Network.

On June 18, Trump officially launched his 2020 campaign to seek a second four-year term. More than 20 Democrats are campaigning for their party’s nomination to run against Trump.

The administration has not said how much Trump’s pumped-up July Fourth celebration will cost. The Pentagon postponed a military parade planned for last November after it estimated it could cost $90 million.

The National Park Service is diverting about $2.5 million in entrance and recreation fees primarily intended to improve parks to cover costs associated with the celebration, the Washington Post reported, citing unnamed sources.

The agency did not immediately respond to a Reuters request for comment on the report.

“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 Fourth plans, which reportedly include special access to the National Mall for the politically connected,” Democratic Senator Tom Udall said in a statement.

A VIP section set up near the Lincoln Memorial will be open to government officials and lawmakers, according to a White House official speaking on condition of anonymity. In previous years, government officials and other VIPs have watched the fireworks from the White House lawn.