Paneuropean Union – Bernd Posselt, chair of the Paneuropean Union in Germany, said Otto was "the last grand architect of European unity from the pioneer generation." Zoltán Wodianer-Nemessuri, chair of the Paneuropean Union in Hungary, stated: "He deserves undying respect in Hungary (for doing) by far the most to ensure that the 1956 Hungarian Uprising should not fade from public memory".