Kulkarni told TimesNow news channel that Advani, who he said was the "tallest leader" in the BJP after Vajpayee, was not in favour of declaring Modi the Bharatiya Janata Party's prime ministerial candidate.
"He is not in favour (of this decision)," Kulkarni said.
Kulkarni, who was also close to former prime minister Atal Bihari Vajpayee, accused Modi of polarising the BJP and questioned his ability to head a stable central government.
"A socially polarising leader has polarised his own party. Can he run a smooth, stable and effective government at the centre? Think seriously," Kulkarni asked in a tweet.
Kulkarni was part of the BJP's strategy team in the 2009 Lok Sabha election and worked closely with Advani. He served as Vajpayee's speech writer and media adviser. Kulkarni is no longer a member of the BJP.
--IANS (Posted on 12-09-2013)