Republican. The idea that David Cameron and Barack Obama are extremely similar is extremely inane.
I would argue that they are more similar to each other than Dubya and Blair (for example) are.
Anyway, it's obvious to any reasonable person that Fillon would be a member of the Peace and Freedom Party.
I definately agree that Obama and Cameron are more similar than Bush and Blair (but that being said David Cameron was never very conservative even for European standards), but Fillon is a Catholic social conservative and an economic Thatcherite, I don't see how he would fit into the Democratic Party, if that's what you're refering to when you say ''Peace and Freedom Party''.