I find it interesting that many Prime Ministers of France are appointed even though they are at times members of the opposing party of the sitting president. Euen more so considering that Prime Minister seems to be a stepping stone to the French presidency.
The Constitution says that the Prime Minister must be appointed by the president among the deputies and they must vote wether to validate the president's choice or not.
Before 2000 the deputies were elected for 5 years and the president's mandate was for 7 years so, sometimes, the president had to choose a member of the a party different from his 'cause that party had the majority in the
Assemblée (it happened twice since 1958 : 1986-1988 and 1997-2002). But since 2000, the president's mandate is of 5 years and the deputies are elected about a month after so the PM is always in the sae party as the president so he's not as important as he used to be. Some people say that there shouldn't be a PM, that PMs are useless. I quite agree.
That 2000' law was a trick played on the people by the politicians it was passed by popular vote (referendum) but they never mentioned the part where the deputies and the president will be choosen almost at the same time, they mostly talked about it as reducing the president's mandate and most people agreed 'cause they thought it would grant them the possibility to cange him within 5 years instead of 7 if they are unhappy with him (and, in 2000, many people were unhappy with the president) but it was a trick 'cause in fact, it removed mid-term elections. so now the government can do whatever he wants for 5 years before having to face, though vote, the consequences of its politics.