Mukherjee was sidelined from Congress during the premiership of Rajiv Gandhi. Mukherjee had viewed himself and not the inexperienced Rajiv, as the rightful successor to Indira following her assassination in 1984. Mukherjee lost out in the ensuing power struggle. He formed his own party, the Rashtriya Samajwadi Congress, which merged with Congress in 1989 after reaching a consensus with Rajiv Gandhi. After Rajiv Gandhi's assassination in 1991, Mukherjee's political career was revived when Prime Minister P. V. Narasimha Rao appointed him Planning Commission head in 1991 and foreign minister in 1995. Following this, as elder statesman of Congress, Mukherjee was the principal architect of Sonia Gandhi's ascent to the party's presidency in 1998.