Johnston is set to stand down this week after successfully overseeing what has been a turbulent period in the Glasgow club's history.
And, in a significant development for the Scottish champions, it appears Whyte is poised to assume his responsibilities.
The multi-millionaire businessman kept a low profile during his take-over of his boyhood heroes and had been widely expected to take a back seat in the day-to-day running of Rangers.
However, it seems that the Motherwell-born venture capitalist is keen to play an active part in ensuring the continued success of the club on and off the park. To be appointed chairman, he will have to show he is a 'fit and proper person' and prove that in the last five years he has not been debarred as a director of a company.
Johnston said: "As it stands, I am still chairman, but that's merely procedural and because of paperwork being worked upon with Craig Whyte.
"My two-year stint is ending and I'll simply go back to being a fan. I was in the Far East on business last week, but managed to get back to the game at Kilmarnock before attending the SPL title party.
"It was a great way for Walter to sign off as manager. He has very much been a cornerstone for the club over the past few years and has shown great leadership."
Johnston, a senior executive with IMG, was delighted to leave the club after Smith, whom he persuaded to stay on for a final year, had led the club to the Co-operative Insurance Cup and Clydesdale Bank Premier League.
And he expressed confidence that Ally McCoist, who has now taken over from his mentor as manager, will prove a success
He said: "Martin Bain had been working hard on Walter during that period to try to keep him because we all knew how important that could be.
"I then came into it with my own input and I would very much like to think I had some influence."
Johnston added: "I don't think Rangers can replace him as a figurehead and a leader, but I do think Ally McCoist can be successful as manager.
"He is strong-minded, but will need to be. He's had an apprenticeship with one of the best and hopefully that will be prove significant."