With Gelasius's death at Cluny on 29 January 1119, Cardinal Lamberto and Cardinal Cono (Bishop of Palestrina) conducted the election of a new pope according to the canons. Cardinal Lamberto carried out the coronation of Guy de Bourgogne at Vienne on 9 February 1119, and became a close advisor of Pope Callixtus II. Accompanying Callixtus throughout France, he assisted Callixtus in his initial dealings with Holy Roman Emperor Henry V. As a well-known opponent of the emperor's right to select bishops in his territories (the Investiture Controversy), Lamberto was a natural choice for papal legate. He was sent in 1119 to deal with Henry V and delegated with powers to come to an understanding concerning the right of investiture.