 In 1818 Sailer declined the offer of the Prussian Government to appoint him as Archbishop of Cologne; in 1819 the Bavarian Government, through the influence of the Crown Prince Louis, nominated him as Bishop of Augsburg, but the nomination was rejected by the Vatican.In 1821, however, after he had sufficiently justified himself, Sailer was appointed cathedral canon of Ratisbon, in 1822 as auxiliary bishop and coadjutor with right of succession, in 1825 as cathedral provost, and in 1829 as Bishop of Ratisbon.As bishop he supported his choral vicar Karl Proske, in Proske's attempts to revive ancient church music.