The BJP will decide on Wednesday what action - if any - should be taken against the 13 state legislators who defied orders and attended a rally yesterday called by BS Yeddyurappa.
Mr Yeddyurappa has quit the BJP and formed his own party, the Karnataka Janata Paksha (KJP). He says that if the BJP has the courage, it should punish its members who supported him.
That is a challenge for the BJP because if it delivers on its threat to suspend members who support Mr Yeddyurappa, its government will be reduced to a minority in the Karnataka Assembly.
Mr Yeddyurappa has dared the BJP to accept that it has lost its majority and face elections.
He has accused the BJP of betraying its promise to reinstate him in a position of power in the last few months.
Mr Yeddyurappa was made to quit as chief minister of Karnataka in July 2011 after he was encircled by a series of corruption charges.
Mr Yeddyurappa's rally in Haveri in North Karnataka was attended by one lakh supporters.
His power is derived largely from his stature among the upper-caste Lingayat community, a crucial vote bank for the BJP.
Current chief minister Jagadish Shettar is also a Lingayat. When the BJP made it clear that Mr Yeddyurappa could not head the government, he picked Mr Shettar as his replacement in July this year but their relationship has turned acrimonious over the last few months.
Here is the math: the BJP rules Karnataka with 118 MLAs in a 225-member house. Mr Yeddyurappa claims that he has the support of 50 of them, but has not been able to prove this - 13 were at his rally yesterday.