Party What Communist Party In The EU Today Is Most Existent And Powerful?

What Communist party in the EU today is most existent and powerful? - party

Most of the pieces that dominate the Labor Party and the Socialist appear. It seems to spread throughout Europe, the communist parties, however. In other words, this party may be a majority of seats in Parliament, what was once the country? And if that party has control at the local level (eg a city like Rome), how it works in the effieciently ideology?