After the Archbishop Otto of Trier had died in 1430, Pope Martin V appointed the Speyer bishop Raban of Helmstatt his successor. Nevertheless, the Electorate was contested by opposing parties, and in 1432 Nicholas attended the Council of Basel representing the Cologne dean Ulrich von Manderscheid, one of the claimants, who hoped to prevail against the new Pope Eugene IV. Nicholas stressed the determining influence of the cathedral chapter and its given right to participate in the succession policy, which even places the pope under an obligation to seek a consent. His efforts were to no avail in regard to Ulrich's ambitions; however, Nicholas's pleadings earned him a great reputation as an intermediary and diplomat. While present at the council, he wrote his first work, "De concordantia catholica" ("The Catholic Concordance"), a synthesis of ideas on church and empire balancing hierarchy with consent. This work remained useful to critics of the papacy long after Nicholas left Basel.