In 1857, he became a Dainagon (Major Counselor) and in the following year he advocated a theory of 'Kobu Gattai' (union of the imperial court and the shogunate), arranging a reconciliation between the court and the shogunate in terms of an issue of the bakufu seeking imperial sanction to the treaties with the West ('Joyaku chokkyo mondai' in Japanese) and a friction caused between the two candidates for the 14th Shogun's post, Yoshinobu HITOTSUBASHI and Yoshitomi (the future Iemochi) TOKUGAWA ('Shogun keishi mondai' in Japanese).
安政4年（1857年）大納言となり、翌年には公武合体を唱え、また条約勅許問題や将軍継嗣問題において朝幕間の調停に努めた。