Antipope Felix V
Antipope Felix V made him the legate to the Diet of Frankfurt to the court of Emperor Friedrich IV. He was further involved in the unsuccessful efforts to win over Europe's princes to Basel's antipope. In order to make an end of the schism the former cardinal advised Felix V to abdicate at which stage Pope Nicholas V restored the cardinal to all his honors and appointed him as a papal legate to the German kingdom] in 1449; his full restoration was on 19 December 1449. He was granted back his titular church as well and from that moment until his death served as the Protopriest of the College of Cardinals. It was due to his estrangement to the Roman see that he was not permitted to participate in the conclave of 1447. He returned to his former archdiocese where he dedicated himself with great zeal to the catechetical formation of the people.