"Narendra Modi is the Prime Ministerial candidate of BJP-led NDA. There is no question of finding a more acceptable Prime Ministerial candidate as a compromise if we come to power," he told reporters here.
Singh was asked about the perception of Modi having a "dictatorial mindset" that could lead some NDA constituents to oppose his name for the top job.
He ruled out such an eventuality and stoutly defended Modi saying "if he had a dictatorial attitude, he would not have been a popularly elected Gujarat Chief Minister."
Singh claimed the number of parties pledging support to NDA had gone up to 25, the latest entrant being TDP, and maintained the BJP-led front was poised to get a clear majority.
To a query, the BJP chief said all issues mentioned in the party manifesto were within the framework of Indian Constitution.
Singh also defended BJP General Secretary Amit Shah, a close Modi aide who is under fire for alleged hate speech, and rejected the charge that his recent remarks at a poll rally in Uttar Pradesh had communal overtones.