Translate the following English sentence to French:
"Moreover, Article 191 of the Treaty (ex Article 138a) stresses, political parties are, I quote, "important as a factor for integration within the Union" ."
D' ailleurs, l' article 191 du Traité (ex 138 A) souligne, je cite, leur "rôle important en tant que facteur d' intégration au sein de l' Union".