WASHINGTON (AP) — It’s no simple matter to move the commander in chief from point A to B, and it’s even more complicated when the president is seeking a second term.

President Joe Biden recently spent three days in Pennsylvania, a pivotal state in the 2024 campaign, and he plans to be in Virginia and Florida this coming week. The Democratic incumbent is seeking an edge over Republican Donald Trump as he ramps up his travels around the country.

Here’s a look at how much it costs and who pays the bill during the campaign season.

HOW MUCH DOES IT COST?

It’s not cheap to fly the president’s fleet.

The White House uses Sikorsky helicopters known as Marine One when the president is aboard, as well as custom Boeing 747s that are immediately recognizable as the iconic humpback Air Force One. (Sometimes the president uses a more modest modified 757 if his destination is nearby or if a runway isn’t long enough to accommodate the bigger plane.)

Marine One costs between $16,700 and almost $20,000 per hour to operate, according to Pentagon data for the 2022 budget year. Air Force One is even more expensive: roughly $200,000 per hour.

But those figures only scratch the surface of the real cost. There also are military cargo planes that travel ahead of the president to make sure his armored limousines are in place, not to mention the enormous security apparatus that follows the president everywhere.

New aircraft are in the works because the current versions are decades old. Sikorsky is producing 23 updated helicopters to serve as Marine One. Boeing is building two new Air Force One planes, and they are scheduled to be finished by 2028. According to the Pentagon, the planes will come with all enhancements, including “a mission communication system,” a “self-defense system” and even “autonomous baggage loading.”

WHO PAYS FOR THE TRAVEL?

When the president flies for political purposes, the campaign is supposed to pay the bill. But during an election year, the line between governing and campaigning can be fuzzy.

For example, Biden held an official event Wednesday in Pittsburgh, where he announced his proposal for higher tariffs on steel imported from China. The event, however, was a not-so-subtle opportunity for the president to rub shoulders with union members who are critical to his reelection, and he jabbed at Trump in his remarks. (At one point Biden joked that the former president was “busy right now,” a reference to the hush money trial that recently got underway in New York.)

It’s up to the White House counsel’s office to figure out what percentage of the president’s travels are campaign related. That determines how much the federal government should be reimbursed by the Biden campaign. Sometimes the calculations aren’t straightforward, such as when the White House adds an official event to an otherwise political trip.

Norm Eisen, a White House ethics lawyer under President Barack Obama, said both Republicans and Democrats have usually hewed closely to regulations.

“We had a set of rules on how to do the allocations,” he said. “They’re intricate, and we stuck to them.”

No matter what, taxpayers end up on the hook for most of the cost. Campaigns do not pay for all the Secret Service agents and the rest of the security apparatus. In fact, they usually only cover the cost of Air Force One passengers who are flying for explicitly political purposes — sort of like buying a ticket on a particularly exclusive private jet.

HOW MUCH HAS BIDEN PAID?

Biden’s campaign and his joint fundraising committee have been stockpiling travel cash in an escrow account maintained by the Democratic National Committee. From January 2023 until the end of last month, they deposited nearly $6.5 million.

Some of that money goes to general campaign logistics, such as staff expenses and advance work. The account is also used to reimburse the federal government for official aircraft used to transport the president, the first lady, the vice president and the second gentleman when they travel for the reelection effort.

So far, not much money has found its way back to the U.S. Treasury. As of the latest data available, just $300,000 has been provided.

It’s safe to assume that Biden’s campaign will end up forking over much more than that once the campaign is over. Trump’s team reimbursed the federal government nearly $4.7 million for travel expenses during the 2020 race.

But Biden probably won’t have trouble covering his bills. His campaign and the DNC had more than $192 million in cash on hand at the end of March.