Tapped to lead a Franco-Italian carmaking giant formed by merging Renault SA and Fiat Chrysler Automobiles NV, Jean-Dominique Senard is in Tokyo to make what may be the sales pitch of his career.

In an interview Thursday, he painted a picture of a grand alliance making and selling cars across the globe, keeping people employed and churning out profits.

Convincing the stakeholders of the two auto firms on the merits of a merger may have been the easy part. The hard task is selling the deal to Renault¡¯s alliance partner Nissan Motor Co., as well as labor groups and politicians wary of job cuts.