He made the comment when asked why BJP leaders in Bihar were raising the issue of caste of Narendra Modi when the party claimed to be against casteism.
He, however, corrected himself and asked reporters to substitute the word politics for DNA.
He recalled that Chief Minister Nitish Kumar had opposed candidature of Narendra Modi for the prime ministerial post.
"Kumar and Arun Jaitley had met me and the issue was raised by Kumar," Gadkari, who was the BJP president at the time said.
On withdrawal of JD(U) candidate Akhtarul Iman from the contest in Kishanganj, Gadkari alleged it was done in collusion with the Congress to benefit its candidate Maulana Asrarul Haque.
When power went off in the midst of the press conference, Gadkari used it to take a swipe at Kumar.
"People from Bihar will go to Nagpur to see uninterrupted power supply to farmers there. On the other hand, Bihar with so much of electricity generation capacity is battling a power problem," he said.