Veteran Congress leader N.D. Tiwari joins BJP
The two joined the BJP at the residence of party president Amit Shah.
Tiwari is the only political leader to have become the chief minister of two states - Uttar Pradesh and Uttarakhand.
He also served as Minister for External Affairs in Prime Minister Rajiv Gandhi's cabinet.
Tiwari also served as Governor of Andhra Pradesh from 2007 until 2009.