From about 1498, power in Moldavia quietly shifted toward a group of boyars and administrators, comprising, among others, Luca Arbore and Ioan Tăutu. Stephen's son and co-ruler, Bogdan, was also taking on princely responsibilities from his father. He conducted the negotiations with Poland about a peace treaty. The treaty, which Stephen ratified at Hârlău in 1499, put an end to Polish suzerainty over Moldavia. Stephen again stopped paying tribute to the Ottomans in 1500, although by then his health had declined. In February 1501, his delegation arrived in Venice, asking for a specialist doctor. As reported by Marin Sanudo, his envoys also discussed the possibility of Moldavia and Hungary joining the Ottoman–Venetian War. The Doge of Venice, Agostino Barbarigo, sent a physician, Matteo Muriano, to Moldavia to treat his counterpart.