Hillary Clinton will be hitching a ride to Charlotte, North Carolina on Air Force One on Tuesday and Donald Trump wants to know who’s paying for it.

“Why is President Obama allowed to use Air Force One on the campaign trail with Crooked Hillary?” Trump tweeted. “She is flying with him tomorrow. Who pays?”

In all likelihood, it will be American taxpayers who will pick up the tab for a move that’s aimed at making Hillary look presidential.

The pair will be appearing together at the Charlotte Convention Center Tuesday afternoon, according to the candidate’s website.

“In Charlotte, Hillary and President Obama will talk about building on the progress we’ve made and their vision for an America that is stronger together,” the event listing reads.

Obama isn’t the only senior government official to be appearing with the only presidential candidate under FBI investigation.

Vice President Joe Biden will be with Clinton in Scranton, Pennsylvania on July 8th, according to a site that tracks the Clintons’ events.

As to what Clinton will actually pay, that’s unclear.

Time’s Zeke Miller reports the White House counsel will determine that “months after trip.”