The company said Tuesday that it "considers a further development of the management structure of the group" and that "this could include a change in the position of the chairman of the board of management", the German term for CEO.
The firm said Mueller had already indicated his "basic willingness to play a part in the changes".
Volkswagen said in a short statement that board of directors Chairman Hans Dieter Poetsch was in discussions with top managers about their duties and that the result was "currently open".
Two people close to the matter told Reuters that Volkswagen, still struggling to put its emissions scandal behind it, was set to name VW brand chief Herbert Diess as his successor. Volkswagen has the added twist of a complicated ownership structure, with the Porsche-Piech families de-facto controlling the manufacturer and the state of Lower-Saxony, where VW's main facility is based, owning an additional 20%.
As Diesel Scandal Fades, VW Is Planning to Replace Its CEO
Mueller would be the second CEO at a major German company to be replaced this week, after Deutsche Bank AG tapped Christian Sewing to succeed John Cryan on Sunday.
In the aftermath of the diesel-cheating scandal, Volkswagen has been pushing to overhaul its rigid top-down management structure, delegating more responsibility to its brand and regional chiefs.
The contract of 64-year-old Mueller, who took the reins at VW a week after its "dieselgate" emissions test-cheating scandal was revealed in September 2015, runs out in 2020. But he also faced skepticism about whether he was a credible change agent since he started working for Volkswagen in 1978. Diess joined VW from southern-German rival BMW in mid 2015, months before the diesel crisis erupted. The company also makes cars under the Audi, SEAT, Skoda, Bentley, Bugatti, and Lamborghini brands.