With the current French system, a party able to gather 15% of the votes in the legislative elections can act as major spoiler if not negociated with, or having its program applied (as Sarkozy did with Le Pen's).
Trotskyites+PCF+altermondialists+Green gets you way above that percentage. Of course, building a party that could attract all these voters is a major task. But then, unifying Neo-Pagans and über traditionalists on the far right mustn't have been much easier. Un roi sans divertissement est un homme plein de misères