U.S. Secretary of Defense Leon Panetta was said to be lifting a ban on women soldiers serving in combat. Women in recent years have served on the front lines as helicopter pilots and emergency healthcare professionals.
McCain, ranking member of the Senate Armed Services Committee, said he respected Panetta's position.
"Many (women) have made the ultimate sacrifice and our nation owes them a deep debt of gratitude," he said in a statement.
Sen. James Inhofe, R-Okla., serving on the same committee, said he didn't believe there would be a significant combat role for women in the armed services because of physical barriers.
McCain expressed similar concerns, saying it was "critical" for defense leaders to hold women to the same performance benchmarks as men serving in a similar capacity.
Sen. Kirsten Gillibrand, D- N.Y., also on the armed service committee, said the Defense Department's expected decision was a step in the right direction as women seek to advance their military careers.
"This decision finally opens the door for more qualified women to excel in our military and advance their careers and obtain all of the benefits they have earned," she said in a statement.