By Costas Pitas

(Reuters) – The Boeing Next-Generation Presidential Aircraft (NYSE:) is at risk of further delays due to a tight labor supply and lower than expected security clearance rates. This was disclosed Wednesday by the congressional investigative arm.

According to the U.S. Government Accountability Office, Boeing’s need to find an alternate supplier for interior work was also cited by them as a serious schedule risk.

Air Force One is known worldwide as the airborne White House because it features the American flag, “United States of America”, and the seal of government.

This aircraft is 4,000 feet (372 meters) in size and has three levels. It includes a conference room, medical suite, and an additional conference room.

Boeing 747-8s can fly in any security scenario, including nuclear war. They are equipped with advanced communication and military avionics.

In 2018, Boeing was awarded a contract worth $3.9 billion for the delivery of two 747-8 planes. This aircraft will be in service around 2024. According to the Pentagon, these planes will not be delivered before 2026.

GAO stated in its report that Boeing has limitations to its aircraft mechanic workforce due to a highly competitive labor market.

They stated that another limitation was lower than planned security clearance approval rates for qualified workers who are required to modify aircrafts.

Boeing has not yet responded to my request for comment.

Donald Trump took a pledge from Dennis Muilenburg, then Boeing CEO, that the replacement of Air Force One would be less expensive than $4 billion in December 2016.

Trump previously urged Trump to stop buying the new Boeing Air Force One, claiming that it was too costly and ridiculous.