Leader of the Opposition in Rajya Sabha Arun Jaitley was also present in the meeting.
Modi's meeting with Singh and Jaitley came a day after the chief minister's one-on-one meeting with RSS chief Mohan Bhagwat in Nagpur yesterday.
BJP is likely to make announcements about allocation of responsibilities to its General Secretaries and office bearers tomorrow after a Parliamentary Board meeting.
The Parliamentary Board, the party's highest decision-making forum, will also discuss BJP's strategy for the monsoon session of Parliament beginning on August 5.