WASHINGTON — The F-35 Joint Strike Fighter's record on cost, schedule and performance has been a scandal and a tragedy, the chairman of the Senate Armed Services Committee told senior Pentagon officials Tuesday during a withering critique of the most expensive weapons program in U.S. military history.

Sen. John McCain, R-Ariz., said during an oversight hearing held by the committee that the aircraft's development schedule has stretched to 15 years, deliveries of the F-35 have been delayed, and costs have skyrocketed.

"It's been a scandal and the cost overruns have been disgraceful," McCain said. "And it's a textbook example of why this Committee has placed such a high priority on reforming the broken defense acquisition system."

Pentagon acquisition chief Frank Kendall and Air Force Lt. Gen. Christopher Bogdan, the F-35 program manager, said the they are "making solid progress" with the F-35 and are confident of overcoming the challenges.

"The F-35 is no longer a program that keeps me up at night," Kendall said.

BEAUFORT, SC - MARCH 08: (EXCLUSIVE COVERAGE) The F-35B Lightning II fifth generation multi role combat aircraft showing the vertical lift fan, at Marine Corps Air Station Beaufort on March 8, 2016 in Beaufort, South Carolina. UK personnel from the Royal Navy and RAF are embedded with the US Marine Corps on the F-35 operational training programme, based in Beaufort, South Carolina. This includes pilots and engineers, with numbers of UK personnel starting to grow in the build to the reforming of 617 Squadron (the Dambusters) in summer 2018. The Dambusters will reform at Beaufort before returning to the UK, to be based at RAF Marham. (Photo by Jeff J Mitchell/Getty Images)

The F-35B Lightning II fifth generation multi role combat aircraft showing the vertical lift fan, at Marine Corps Air Station Beaufort on March 8, 2016, in Beaufort, South Carolina.

Photo Credit: Jeff J Mitchell/Getty Images

× Fear of missing out? Sign up for the Early Bird Brief - a daily roundup of military and defense news stories from around the globe. Thanks for signing up. By giving us your email, you are opting in to the Early Bird Brief.

The Pentagon plans to spend close to $400 billion to buy nearly 2,500 F-35s for the Air Force, Navy and Marine Corps. The budget request for fiscal year 2017 includes $8.3 billion to purchase 63 aircraft. The F-35, which is being designed to meet the specific requirements of each of the services, cost over $100 million each. Bogdan said he anticipates reducing the per-unit cost of the Air Force's version to under $85 million by 2019.

McCain quizzed Bogdan on how many people are needed to oversee the F-35 program. The general told him there are about 2,600 people and it costs $70 million a year to operate the program office.

"The information that I have is it's nearly 3,000 (people), and the cost is $300 million a year, "McCain said. "But $70 million a year to run an office is ... pretty disturbing."

Copyright 2016 The Associated Press. All rights reserved. This material may not be published, broadcast, rewritten or redistributed.