 Rabbi Leiner was the right-hand man of the Kotzker rebbe, Rabbi Menachem Mendel of Kotzk, by whom he was charged with overseeing the Hasidim.In 1839 Leiner had a public and dramatic falling out with the Kotzker Rebbe.On the day after Simchat Torah of that year, Leiner left Kotzk with many of his followers to form his own hasidic circle.