Kumar appealed to all JD(U) MPs including Sharad Yadav, whom he met here, to denounce the decision and quit the party. He even offered to resign from his Rajya Sabha seat.
"As far as Kerala is concerned we will never become the part of the JD(U) represented by Nitish Kumar. Future course of action will be decided after the state council meeting," he told reporters here.
Kumar accused the Bihar chief minister of "sabotaging" the party's decision to form the Mahagathbandhan (Grand Alliance) "which was not just for Bihar, but for the whole nation".
"We will not agree to this, whatever be the price we have to pay for it," he said.
More From This Section
Bihar Chief Minister Nitish Kumar unexpectedly resigned yesterday, but joined hands with friend-turned-foe-turned- friend BJP to reclaim the government.
The Rajya Sabha MP also said it was unfortunate that Nitish allied with those having "fascist tendencies", contrary to the expectations of people, party men and the party resolution adopted in the last national conference.
With this, the party resolution to protect securalism and fight against "fascist forces" has been thrown into the dustbin, the MP added.
"We cannot tolerate Hindutva in the sense they (BJP) talk about it. What is happening is in every sphere of life there is a pressure to make it (Hindutva) a monolithic structure. We cannot accept that," he said.
The Kerala JD(U), a partner in the Congress-led UDF opposition in the state, had opposed the party's central leadership's decision to vote for the NDA's Ram Nath Kovind during the presidential poll
He was a minister in the United Front government after being elected to the Lok Sabha in 1996 on Janata Dal ticket.
Kumar was in Janata Dal (Secular) headed by former Prime Minister H D Deve Gowda from 1999 to 2010, when Janata Dal had broken into many factions after some of its leaders decided to join hands with BJP-led NDA at the Centre.
The Kerala leader parted ways with the JD(S) and formed the Socialist Janata (Democratic) Party in 2010.