It's one thing to utilize Air Force One to transport the president from point A to point B during his term. It's a massive undertaking, and always expensive. 

But it gets a little tricky for a president who's seeking a second term in office. One might ask who foots the bill for the president's usage of Air Force One to fly to various campaign stops for months on end?

Technically, when a president utilizes a plane from the Air Force One fleet (there are several) to fly to campaign stops and for campaigning purposes, his campaign is supposed to foot the bill for his travels.

But as noted in an AP report, "the line between governing and campaigning can be fuzzy."

What's going on?

One can see the obvious loophole. For instance, Biden travels to Pennsylvania to address a political issue as it's related to his office, and while he's there, he might make a campaign pitch or three.

"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," the AP noted, while providing an example.

The AP wrote:

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.

In this instance, and many like it, it's up to White House attorneys to determine how much they should reimburse the federal government (U.S. taxpayers) for trips that involve official business mixed with campaigning.

Previous White House ethics lawyers have stated that the numbers are closely watched.

However, for instance, Trump's campaign reimbursed the U.S. Treasury over $4 million by the time the campaign was finished. So far, the Biden campaign has only reimbursed $300,000.

How much does it cost?

It costs a metaphorical arm and leg -- and several other body parts -- to transport the president, his staff, Secret Service members, and coordinate all the logistics that go into any given trip.

"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," the AP noted.

Military cargo planes fly to locations in advance of the president's arrival, which contain his limousines and armored vehicles, along with a massive fleet of first-responder vehicles. That's not to mention the security staff and everything else required for a trip.

Only time will tell what kind of bill Biden racks up for this campaign season, and if he pays it all.