[[Image:Windhorstdenkmal Meppen.jpg|thumb|upright|Memoriale alla scuola di [[Meppen]].]]
Alla morte di [[Hermann von Mallinckrodt]] (1821–1874), Windthorst divenne leader del partito, carica che ricoprì fino alla morte. Sotto la sua guida, a dispetto dei dissidi col governo prussiano, il partitomovimento crebbe considerevolmente, ampliando la sua base di consenso. HeIn wasveste especiallydi exposedleader tocentrista, theentrò attackspresto ofin contrasto col cancelliere Bismarck, whoche attempted,personalmente personally,attuò touna discreditcampagna himdiffamatoria andcontro tola separatesua himpersona, fromtentando thedi restemarginarlo ofdal thesuo partystesso partito. And,Dal hecanto wassuo, byWindthorst farfu thetra ablesti andpiù mostaspri dangerouscritici criticdelle of Bismarck'spolitiche policybismarckiane. The change of policy in 1879 led to a great alteration in his position: he was reconciled to Bismarck and even sometimes attended receptions at Bismarck's house. Never, however, was his position so difficult as during the negotiations which led to a repeal of the [[Kulturkampf|May laws]].
On the background of rising [[anti-Semitism]], he stood up for the [[Jew]]s and enforced the expulsion of anti-Semitic members from the Center Party.
