The 55-year-old has come under attack from some quarters following his appointment by former Aberdeen team-mate Gordon Strachan when he took over as national boss.
McGhee was recently sacked as manager of Bristol Rovers and that followed a torrid spell in charge of Aberdeen.
Speaking at a Hampden Park press conference McGhee said: "I see those two episodes (at Aberdeen and Bristol Rovers) as failures.
"Therefore, as far as I am concerned, I would imagine people would be questioning my ability, my motivation to still be doing the job, all those things.
"I am not the manager, I am not there as the number one, all I can do is give Gordon as much support and make him the best manager I possibly can and hope that people see the job I'm doing and appreciate it.
"I am not going to sit here and go into what happened at Aberdeen and Bristol Rovers, but I feel I have a legitimate right to consider myself as a viable football manager."
McGhee also saw no reason for having to justify his appointment by Strachan.
"You only have to look at the nature of our business," he added. "I am not the only manager who has lost his job and got another job, that's what happens."