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

Donald TrumpDonald John TrumpGOP lawmakers preparing to vote on bill allowing migrant children to be detained longer than 20 days: report Wasserman Schultz: Infants separated from their parents are in Florida immigrant shelters Ex-White House ethics chief: Sarah Sanders tweet violates ethics laws 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 ClintonColorado governor teases possible presidential run Mueller asks judge for September sentencing for Papadopoulos House Judiciary Committee subpoenas FBI agent who sent anti-Trump texts 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.