He was in attendance at the Council of Basle (1431–43). In 1437, he was a member of the conciliar commission that reported on the poor governance of the church by Pope Eugene IV. In the papal conclave of November 5, 1439, he was one of the supporters of Antipope Felix V.
Antipope Felix V made him a pseudocardinal on April 6, 1444 in Geneva, offering him the titular church of San Marcello al Corso. Estaing refused Felix V's offer to make him a cardinal, instead choosing to side with Pope Nicholas V, who absolved him for his earlier support of Felix. In the consistory of December 19, 1449, Nicholas V made Estaing a cardinal priest, awarding him the titular church of Santa Sabina on January 12, 1450. Estaing entered Rome on November 30, 1450 and received the red hat the next day.
On March 1, 1451, he was elected Bishop of Sion, though a dispute with the cathedral chapter ultimately led to his resignation as bishop on September 11, 1454. He was present at the secret consistory of October 27, 1451. He served as Camerlengo of the Sacred College of Cardinals from November 1452 to November 5, 1453. On June 27, 1453, he was elected Bishop of Fréjus, holding this position until his death. He participated in the papal conclave of 1455 that elected Pope Callixtus III.
|Catholic Church titles|
|Camerlengo of the Sacred College of Cardinals
Alain de Coëtivy