His involvement with the educational projects earned him a nickname bakałarz (holder of baccalarius degree, teacher). His involvement with the educational reforms lessened only during the era of the Great Sejm (1788–1792), when he became increasingly involved with the wider reform program. On 29 May 1773 he received the office of Great Clerk (Writer) of Lithuania, a relatively low-ranked position that was seen by some as below the magnates of the Potocki family. He participated in the Partition Sejm of 1773, where he sat on several commissions. Seeing himself in opposition to the king, he refused a seat on the Permanent Council that he was offered in March 1774. The king tried to appease him with the Order of Saint Stanislaus on 14 July that year, but that failed to bring Potocki to his side. Instead, Potocki became, for the next decade and half, one of his chief political critics and opponents; on 1776 he went to Moscow to argue, unsuccessfully, for limiting the power of king and the Russian ambassador, Otto Magnus von Stackelberg. Later that year, his election to the Sejm was disputed, and the king and Stackelberg managed to block his election. In 1778 however, the growing rift between the king and Stackelberg allowed him to take, through political maneuvering, the chairmanship of the Permanent Council Marshal of the Sejm. That year he also became a Knight of the Order of the White Eagle. In 1779 Potocki joined the freemasonry, and by 1780 he advanced to the head of a freemasonry lodge. He became de facto head of the "Familia", and of anti-royal opposition (succeeding its previous leader, Stanisław Lubomirski, upon his death in 1783). That year also saw the sudden death of his wife. During a trip to Italy and France, in absentia, the influence of the Familia resulted in his appointment to the office of the Court Marshal of Lithuania. He continued to oppose various royal projects at the Sejms of 1784 and 1786. In 1785 he lost some face for his involvement in the Dogrumowa affair, in which the king was falsely accused of an instigation of a poisoning attempt. Disappointed with Russia's lack of support for any serious reforms in Poland, he shifted to favoring an alliance with the Kingdom of Prussia instead. Although this resulted in the split of the anti-royalist opposition, he was seen as the leader of opposition (the Patriotic