Dean of the College of Cardinals
The next year, de' Medici was raised to Cardinal Bishop of Sabina, but opted for the suburbicarian see of Frascati seven months later. On 29 April 1652 he was made Cardinal Bishop of Porto e Santa Rufina and Vice-Dean of the College of Cardinals. On 23 September the same year he became Dean of the College of Cardinals and Cardinal Bishop of Ostia e Velletri. He presided over the conclave of 1655 and announced the papal election of Pope Alexander VII.