Labelling the Congress and the BJP as "A and B teams", he said both the parties would not cross the figure of 125 seats in upcoming general elections.
In an oblique reference to Narendra Modi, Yadav said "the projection of any name as Prime Minister, particularly of a Chief Minister, can't lead a party to form government at the Centre."
He said a third front was possible only when his party was part of it.
The master-key would be in the hands of regional parties, he said.
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On VHP's Ayodhya yatra, he said it was untimely and politically-motivated.
The JD(U) chief was talking to reporters here on the sidelines of a function to commemorate the death anniversary of Akali leader Sant Harchand Singh Longowal organised under the aegis of Sanjha Morcha.
The Sanjha Morcha is a conglomeration of the Peoples Party of Punjab (PPP), the SAD (Longowal) and Left parties in Punjab.