Poll strategist-turned-activist Prashant Kishor on Sunday alleged that age was catching up with Bihar Chief Minister Nitish Kumar, who was also feeling "politically isolated, after being surrounded by people whom he did not trust".

Kishor made the stinging remarks in response to the statement by 71-year-old Kumar the day before that the former was working for the BJP and had once advised him to merge the JD(U) with the Congress.

"Slowly, age seems to be catching up with Nitish Kumar and he seems to be growing delusional," said Kishor, who has earlier worked with the Bihar CM both as a professional and a party colleague.

"Kumar starts speaking one thing and ends up speaking something altogether different. If he believes I am working for the BJP, why would I suggest a move that could strengthen the Congress," the 45-year-old activist, who is currently on a 3,500-km-long 'pada yatra', covering every nook and corner of Bihar, said in a short video statement.

Nitish keeps uttering things which have no meaning, the founder of political consultancy firm I-PAC claimed.

"The English word delusional fits Nitish Kumar perfectly. He is feeling politically isolated as he is surrounded by people whom he does not trust. This has left him fearful and in trepidation he keeps saying things that have no meaning," added Kishor, who has been critical of the JD(U) leader's frequent change of alliance partners.