Kumar along with Rashtriya Janata Dal (RJD) chief Lalu Prasad Yadav will be launching a signature campaign 'shabd wapasi' tomorrow against Modi's remark.
"Inspite of our repeated pleas, Modiji hasn't retracted his derogatory remarks on our DNA. We're going to launch a ' shabd wapasi' campaign against him," tweeted Kumar.
The chief minister added that 50 lakh people from Bihar would be a part of 'shabdwapasi' signature campaign and would be sending DNA sample test to Modi.
While addressing a rally in Muzaffarpur on July 25, Modi remembered the way Kumar had invited him to dinner and later cancelled the invitation.
Modi said that Kumar had not only disrespected him but also a 'mahadalit' like former Chief Minister Jitan Ram Manjhi.
"There seems to be some problem in his DNA because the DNA of democracy is not like that. In democracy you respect even your political rivals," Modi had said at the rally.
Earlier, Kumar had written an open letter to Modi over the issue.
Inspite of our repeated pleas Modiji hasn't retracted his derogatory remarks on our DNA, we're going to launch शब्दवापसी /TakeBackYourWords
— Nitish Kumar (@NitishKumar) August 10, 2015