The announcement comes months ahead of assembly elections in many states including Kerala, West Bengal, Tamil Nadu and Assam where the BJP is expected to look for alliances.
According to BJP sources, the party is keen to strengthen the National Democratic Alliance (NDA), which has shrunk since the BJP-led NDA lost the 2009 Lok Sabha election.
Among the parties that have moved away from the BJP are the Indian National Lok Dal (INLD), Biju Janata Dal (BJD), Telugu Desam Party (TDP) and various groups in Tamil Nadu.
The sources said the decision to name Jaswant Singh, MP from Darjeeling, must also be seen in the context of the opposition's persistence for a Joint Parliamentary Committee (JPC) to probe the 2G spectrum scam. The entire winter session of parliament was washed out on the issue.