Whatever his future duties, Mr. Gates already has a strong hand in deciding the company’s direction. He remains Microsoft’s chairman and its largest individual shareholder, and he is one of four members of the committee leading the search for the next chief executive. His opinion in the selection process will hold more sway than anyone else’s.

Despite the speculation, it remains a long shot that Mr. Gates will take on bigger day-to-day duties at the company. According to several people close to him, who spoke on the condition that they not be named because their discussions were private, Mr. Gates has no intention of leaving his philanthropic career to work again full time at Microsoft. John Pinette, a spokesman for Mr. Gates, declined to comment.

Still, the narrative of the rescuing founder remains a powerful one, especially since Steven P. Jobs, a rival of Mr. Gates’s, returned to Apple and transformed it into one of the world’s most profitable companies. Microsoft has struggled in important new markets in recent years, particularly with mobile phones and tablets, leading some executives in the tech industry to call for Mr. Gates to return as chief executive.

The search for Mr. Ballmer’s replacement is still in its early stages. Although the process could suddenly accelerate, the board is in no hurry to act before the end of the year, said a person briefed on the succession plans.