[1] He was chosen by the Venetian Senate to accompany Henry I, Duke of Guise, on his visit to the Republic of Venice in 1583.
The election was confirmed by the Pope only on 12 May 1608 because of the Venetian Interdict, a heavy diplomatic quarrel between the Papal Curia and the Republic of Venice during which Vendramin left the government of the Patriarchate to a vicar.
[2] In the next two years Vendramin aligned so much himself with the politics of the Papal Curia that on 15 January 1610 the Full College (i.e. the government of the Republic of Venice) formally rebuked him, and from that moment on he limited himself to ordinary administrative episcopal acts.
In Venice, on 18 January 1617 he consecrated the church of the Benedictine nuns in San Zaccaria and took care of the restoration of the Patriarch's Palace, not forgetting to make generous donations to the poor and to the cult of the Blessed Virgin Mary.
A marble relief by Michele Fabris shows the presentation of the cardinal's hat by Pope Paul V to Vendramin.