Two ministers have resigned this morning. CM Udasi and Shobha Karandlaje are likely to defect to the new party founded by BS Yeddyurappa, who quit the BJP late last year.
Another 14 state legislators say they want to quit the government but the Speaker of the Assembly, KG Bopaiah, is traveling abroad.
The rebels say this is a ruse by the BJP and the chief minister, Jagadish Shettar, to hold onto them.
Even if their resignations are accepted, the government will not fall. 18 legislators must quit for that to happen.
The dissidents want to embarrass the BJP and chief minister Jagadish Shettar ahead of the Budget Session scheduled to start in the first week of February.
Mr Yeddyurappa formed the Karnataka Janata Party or KJP in December after a long and public battle with the BJP over its refusal to confer an important post on him.
He was forced to resign as chief minister in July 2011 after he was indicted for corruption in a report on illegal mining.
Mr Yeddyurappa has also been accused in a series of cases of misusing his term as chief minister for sweetheart land deals for his family.
The BJP was elected to power for the first time in South India in 2009 in Karnataka.
The state votes in the next few months for its next government.