Trump: 'Who pays' for Obama's appearance with Clinton?

Donald TrumpDonald John TrumpHouse Democrat slams Donald Trump Jr. for ‘serious case of amnesia’ after testimony Skier Lindsey Vonn: I don’t want to represent Trump at Olympics Poll: 4 in 10 Republicans think senior Trump advisers had improper dealings with Russia MORE is criticizing President Obama's use of Air Force One to travel to a campaign event in North Carolina on Tuesday with Hillary ClintonHillary Diane Rodham ClintonGrassley blasts Democrats over unwillingness to probe Clinton GOP lawmakers cite new allegations of political bias in FBI Top intel Dem: Trump Jr. refused to answer questions about Trump Tower discussions with father MORE.

“Who pays?" Trump asked late Monday on Twitter, noting that Clinton will fly with Obama.

A White House official told a Time magazine reporter that the Obama administration, like previous administrations, follows “all rules and regulations to ensure that the [Democratic National Committee] or other relevant political committee pays what is required for the President to travel to political events.”

Clinton and Obama will appear together for the first time on the campaign trail in Charlotte, N.C. Trump also has an appearance set in North Carolina on Tuesday, in Raleigh.

Trump on Tuesday called the use of Air Force One a "total disgrace."

This report was updated on July 5 at 7:18 a.m.