A fiery speech is expected from Mr Modi who will challenge the development of Bihar that Mr Kumar is often credited with.
On Sunday, the BJP's Narendra Modi
will address a rally in Patna, his first in three years.
He didn't campaign in the state for as long as his party, the BJP, was co-governing the state with chief minister Nitish Kumar and his Janata Dal United or JD(U).
The alliance was elected in November 2005 and then returned to power in 2010.
But the partnership ground to a squawking halt in June, when Mr Kumar said he could not accept the BJP's decision to place Mr Modi in charge its campaign for the national election. Mr Kumar predicted the BJP's next move would be to pick Mr Modi, a leader he described as divisive, as its candidate for Prime Minister. Three months later, he was proven correct.
Now, the BJP is determined to run a blockbuster show on the weekend to prove that it has done right in standing by its man. Arrangements include an 30-foot stage and a massive electronic screen that will flash images of Mr Modi and notable venues in Bihar, all over the Gandhi Maidan. Eleven special trains and almost 3000 buses have been hired for ferrying people from all over the state.
The BJP hopes that its rally will trump the one that was held by Mr Kumar at the same venue - Gandhi Maidan - in last year November. "I don't make it a habit to comment on rallies by other parties," he said. When asked if he expects his bete noire to take a few swipes at him in his speech, the chief minister said, "Anyone who talks about me will be giving me publicity."
Mr Kumar's political restraining order against Mr Modi ensured that the BJP leader was allowed to address a public gathering just once in the last eight years in Patna - he was among the speakers at a rally held by his party after a session of its national executive in 2010 which was marred by the cancellation of dinner to be hosted by Nitish Kumar who was irked by the fact that Modi decided to give full page advertisement with a photograph of him hugging kumar in Ludhiana NDA rally in 2009 .
This time around, he's expected to compensate with a fiery speech that will challenge the development of Bihar that Mr Kumar is often credited with.