Nissan Motor Co. Chairman and Chief Executive Officer Carlos Ghosn decided to switch his focus to managing the company's alliance with Renault SA and Mitsubishi Motors Corp. as political challenges mount in the U.S. and European markets.

Ghosn, also serving as chairman and CEO of Renault and chairman of Mitsubishi Motors, is aiming to expand the world's fourth-largest automaker alliance after Germany's Volkswagen AG, Toyota Motor Corp. and General Motors Co.

After stepping down as Nissan CEO, he will remain as chairman to oversee Japan's second-largest automaker while Hiroto Saikawa will take over as CEO from April, a position he currently shares with Ghosn.