"Third Front is actually aimed at promoting the interest of Congress," he said addressing party rally while launching a blistering attack on Bihar Chief Minister and JD(U) leader Nitish Kumar, a prime mover of the anti-Congress and anti-BJP Front.
"Did you hear about Third Front a year or six months ago ... It has come (into being) on the eve of elections... It can spoil the elections but can do no good for the country," the BJP prime ministerial candidate said.
Coming down heavily on Congress and other parties, he said while for BJP secularism meant promoting the interests of all castes and communities and ushering the country on the path of development but for the others it has a "narrow meaning of stopping Narendra Modi from coming to power".
Tearing into Kumar's development claims, he quoted statistics stating that only 23 per cent households in the state have toilets and only 16 per cent have electricity.
New entrants to NDA - LJP President Ramvilas Paswan and Upendra Kushwaha of Rashtriya Loksamata Party-- shared the dias with Narendra Modi for the first time after becoming part of the alliance.
Narendra Modi said for the parties opposing him the main agenda is not to protect sovereignty of the country or its development but only to stop him.
"Negativism and efforts to fool the country in the name of secularism will not cut any ice with people any more," he said in an apparent dig at Congress and Nitish Kumar.
Narendra Modi referred to his October 27 rally in Patna which was rocked by a serial explosions that claimed seven lives and blamed Kumar and his "vote bank politics" for it.
"These people who are involved in vote bank politics wanted to end my game through the explosions," he alleged.
Continuing his tirade against Kumar, he said it was due to the "vote bank politics" that Bihar has become a 'haven' for terrorists taking shelter in neighbouring Nepal.
He lambasted Congress and parties seeking to form the Third Front for 'chanting' secularism for everything as part of their 'vote bank politics' and to avoid answering questions on lack of development initiatives.
"Earlier it was a fashion to attribute everything to terrorism from across the border and hands of Pakistan ISI. But today secularism seems to have become the 'jarri butty' (life saving herbs) for everything - be it the question of price rise or corruption," he said and blamed the parties opposing him of practising hypocrisy.
"Today when you say prices of essential commodities are rising, they (opponents) will say secularism is in danger.
There is excessive corruption, they will say secularism is in danger," he added.
Referring to NDA, he said it is witnessing expansion and also stood for National Development Alliance.
"This (the expansion) is not going to stop ... Anxiety of my opponents is set to increase."
Narendra Modi started his 40-minute address in Bhojpuri and lavishly praised Maithli language and 'makhana' known for its nutritional value and grown in north Bihar areas.
This was his third visit to Bihar. After his first visit for the October 27 "Hunkar rally" at Patna, he had visited the state one soon after to condole the death of seven persons in the serial blasts that day.