Why does a French president usually appoint the parliamentary majority’s leader as prime minister during cohabitation?

In the French Fifth Republic, the president typically appoints a prime minister from the parliamentary majority to ensure the government can function effectively when the president’s own party does not control the National Assembly.1

This situation, known as cohabitation, occurs when the president and the parliamentary majority belong to competing political parties. Because the government is responsible for directing national policy and requires the support of the assembly to avoid a motion of censure, a president must appoint a leader from the opposing majority to maintain political stability and avoid a constitutional crisis. By selecting the leader of the majority faction, the president acknowledges the democratic mandate of the assembly, allowing the prime minister to manage internal governmental affairs while the president often retains a primary role in foreign and defense policy.2134