but it seems strange that he doesn’t just appoint the candidate from the left.
From which part of the left? The New Popular Front is actually an amalgamation of broad left wing coalition of various parties. So Macron had to pick from the far-left communist leader Jean Luc Melenchon, or from the centre left Socialist party led by Olivier Faure.
The French legislative assembly works very differently compared to US Congress or the parliamentary system. There isn’t really one, or two, or only five parties getting votes. The French system is much more pluralistic and it is more like a hodge podge of various parties forming a grand coalition that represents an ideology. Even the current French president Emmanuel Macron’s so-called “party”, Ensemble, is a coalition of centrist parties.
If you want to find out more about France’s current deadlock, here is a good succinct video explaining it. www.youtube.com/watch?v=q5Q5nCCF5ck