Social Democrats and the European Left

In countries like france conservative parties have moved as far to the right as possible on issues like migration and crime in a bid to keep their vote from going to far right parties. Have they witnessed a similar problem as social democratic parties if for for different reasons i think if you look at these parties purely in terms of membership statistics there definitely has been a similarly dramatic decline. The threshold for success is always higher on the left than it is on the right so right wing parties always find it easy to govern because capital is already organized.