Singh, accompanied by senior party leaders M Venkaiah Naidu, Arun Jaitley, Ananth Kumar, Ram Lal and S S Ahluwalia, held a long meeting on Suunday evening with Advani to convince him to reconsider his decision to quit.
Party sources said Advani was adamant and "stood firm" on his decision. The issue is also expected to figure in the National Democratic Alliance meeting scheduled for Monday.
BJP, however, maintained that the issue of Leader of Opposition did not come up for discussion during Sunday's meetings.
"This was more of an informal gathering. We discussed the meeting of NDA Chief Ministers and senior NDA leaders to be held tomorrow," Ahluwalia said.
He added that since the BJP Parliamentary Board has turned down the offer made by Advani, it was upto the Board to take a formal call. At the meeting of the Board on Saturday, Advani had expressed his desire not to continue as Leader of Opposition in the new Lok Sabha after the BJP suffered a severe drubbing in the elections.
BJP leaders had requested Advani to reconsider his decision and asked party president Rajnath Singh to make him change his mind. NDA chief ministers would hold a meeting with Advani and other senior leaders on Monday. Another meeting of NDA partners will be also held.
Earlier in the day, senior Rashtriya Swayamsevak Sangh leaders Madan Das Devi, Suresh Soni and Bhaiyyaji Joshi had met Advani to discuss the poll results and the future course of action.
Former BJP leader and Bhartiya Janshakti Party President Uma Bharti also visited the senior leader. After these leaders left, senior BJP leaders V K Malhotra and Najma Heptullah also called on Advani.
Varun Gandhi and Maneka Gandhi, who won the elections from Pilibhit and Aonla respectively also met the leader. BJP election in-charge for Uttar Pradesh Kalraj Mishra also met Advani and gave him a report on the party's performance in the state.