BJP's Sushil Kumar Modi (L) with Bihar Chief Minister Nitish Kumar (R) (File photograph)
When Nitish Kumar pulled the trigger on his 17-year alliance with the BJP, the party's 11 ministers were evicted from the government.
Since then, the BJP says, the Bihar Chief Minister has not invited its legislators and leaders to important government functions, a basic courtesy due to the state's main opposition party.
On Sunday, the BJP's Sushil Kumar Modi tweeted about not being invited to an event in Muzaffarpur where the chief minister inaugurated a thermal power unit. He also warned that in retaliation, the BJP will disrupt all government events to which it is not invited.
"Only JDU MLAs' name in advertisement of Kanti Thermal plant inauguration by Nitish Kumar. This is government function not of JDU. Won't allow the chief minister to address in future," he tweeted.
In June, Mr Kumar truncated his partnership with the BJP and attributed the break-up to its decision to place Narendra Modi in charge of its national campaign. Mr Kumar said this suggested that despite its denials, the BJP was planning to pick Mr Modi as its prime ministerial candidate, which he said he would not support. Mr Kumar is among Mr Modi's detractors who say he has lost the confidence of Muslims after the communal riots in Gujarat. The violence in 2002 took place during Mr Modi's first term as chief minister.