However, when Iesada fell into a critical condition in 1858, the fudai daimyo of the Nanki group appointed Naosuke II of Hikone Domain as a tairo (chief minister) and announced in June in the name of Iesada that the successor was Yoshitomi TOKUGAWA.
だが、安政6年（1858年）、家定が重態となると、南紀派の譜代大名は彦根藩井伊直弼を大老に据えて、6月に家定の名で後継者を徳川慶福とすることが発表された。