Congress veteran Narayan Dutt Tiwari and his son Rohit Shekhar on Wednesday joined the Bharatiya Janata Party (BJP) in the presence of party president Amit Shah.
The 91-year-old leader served as the chief minister of Uttar Pradesh thrice (1976-77, 1984-85, 1988-89) and the chief minister of Uttarakhand once (2002-2007).
In 1986-1987, he served in former prime minister Rajiv Gandhi's cabinet as Minister for External Affairs.
This political development comes ahead of the high-stakes Uttar Pradesh Assembly polls.