Behind the appointment, there seems to have been the support from Shigemune ITAKURA, Kyoto shoshidai (Kyoto deputy), and Katsuyuki SAKUMA (a younger brother of Morimasa), the lord of Naganuma Domain of Shinano Province.
その背景には京都所司代・板倉重宗と信濃国長沼藩主、佐久間勝之（盛政の弟）の力添えがあったようである。