Congressional supporters of the A-10 ground attack plane said on Wednesday that a new nonpartisan report proved the point they've been arguing for years: that the Air Force should keep the Warthog in the skies.

For years, the Air Force has been trying to retire the A-10, saying that it needs to free up funds to begin to bring the F-35 online along with all the maintainers and other staff the new planes require. But lawmakers have prohibited the move and argued that the A-10 is the country's best option for close-air support, pointing to the success it has had in the campaign against the Islamic State. On Wednesday, for example, American A-10s were aiding Turkish and vetted Syrian opposition forces in the battle to retake Jarabulus.

The Government Accountability Office report released Wednesday found that the Air Force does not have enough information to understand the full implications of retiring the A-10 early, including possible gaps in U.S. capabilities. For example, while much attention has been paid to the plane's close-air support mission, the report says the Air Force has not identified how it would replace the A-10's role in search-and-rescue missions.

"At a time of growing threats to our national security, any divestment of this critical aircraft without the fielding of a suitable replacement would leave our men and women in uniform without the best close-air support weapon in our arsenal that is needed now more than ever to meet the challenges of a more dangerous world," Sen. John McCain, R-Ariz., and chairman of the Senate Armed Services Committee, said in a statement.

The report found that the Air Force's savings estimates for A-10 retirement might not be accurate since they do not take into account increased use of other aircraft, McCain said.

The fiscal 2017 National Defense Authorization Act would prohibit the Air Force from retiring the A-10.

Rep. Martha McSally, R-Ariz., and a former A-10 pilot, said she would work to make sure the law requires a fly-off between the A-10 and F-35 before the A-10 is retired.

"Today's report confirms what I've argued continuously — the Air Force's flawed and shifting plan to prematurely retire the A-10 is dangerous and would put lives in danger," McSally said. "I've fought for and won full funding for our entire A-10 fleet and to make the retirement of any A-10 condition-based, not-time based."