He assumed a post of roju (member of shogun's council of elders) in 1610 and became an influential political person under the second shogun, Hidetada TOKUGAWA, and conflicted with a father and son of Masanobu HONDA and Masazumi HONDA who were senior vassals of Ieyasu in the dual political system where Ieyasu, Ogosho (retired shogun), still had an influential power in Sunpu.
慶長15年（1610年）には老中に就任し、第2代将軍・徳川秀忠の政権の有力者となり、大御所となった家康が駿府で影響力を行使する二元政治の中、家康重臣である本多正信・本多正純父子と対立する。