The Edo bakufu (the family of the Tokugawa shogun, which controlled the country) were followers of the Jodoshu sect; the family had a hard time during the Ikko ikki uprising in Mikawa, and continued using 'the Ikkoshu sect' as the formal name.
やがて、全国を平定した江戸幕府即ち徳川将軍家は浄土宗を信仰しており、また三河一向一揆で苦しめられた経緯から一向宗を公式名称として用い続けた。