He served as the fourth General Secretary of the Central Committee of the Communist Party of Vietnam (CPV) 30 March 1938 – 9 November 1940.

After being released from prison, he was introduced by Secretary of the Bắc Ninh Provincial Party Committee Ngô Gia Tự to Secretary of the Haiphong Party Committee Nguyễn Đức Cảnh, who was sent to work at the Vàng Danh mine (Uông Bí) under the alias Phùng.

In September, he was assigned to the Haiphong City Party Committee, then went to work at Mạo Khê mine under the alias Phùng Ngọc Tường.

In 1930, the Communist Party of Vietnam was born, and he was assigned by Nguyễn Đức Cảnh to work in mines in Quảng Yên in Hai Ninh Province.

On February 15, 1931, on the way from Cẩm Phả to Hòn Gai, he was arrested by the French colonial authorities, sentenced to hard labor, and exiled to Côn Đảo.