At an open session of the party in the Bihar town Motihari, Kushwaha made a scathing attack on the BJP and quoted from poet Ramdhari Singh Dinkar's work 'Rashmirathi' the words of Lord Krishna addressed to Duryodhana: "Since gesture of friendship has been spurned, I am announcing the final resolve that henceforth, there would be no more supplication but a war."
He, however, stopped short of announcing a break-up with the BJP-led NDA.
"I have categorically said it is a war. What more do you expect me to say?" he told reporters when asked if he would break his alliance with the BJP.
He also charged Nitish Kumar's government in the state with failure on all fronts.
Kushwaha has often made public his unhappiness over the seat-sharing arrangement for the Lok Sabha polls.
The BJP and the JD(U) offered the RLSP just two seats of the total 40 Lok Sabha seats in Bihar. Kushwaha had said that the number of seats the party was offered was not respectable and asked the BJP to do a rethink by November 30.
The BJP is of the view that his departure, if it does happen, from its alliance will be more than compensated by Bihar Chief Minister Nitish Kumar-led Janata Dal (United), which had fought against the NDA in 2014 but joined it last year.
While, the opposition led by Lalu Prasad's RJD and the Congress believe that if Kushwaha joins their block, then it will be in a stronger position to challenge the ruling alliance in the political crucial state, where the NDA had won 31 of 40 Lok Sabha seats in 2014.
In Lucknow, the announcement by Phule of quitting the BJP was on expected lines as she had been attacking the party from several months.
However, her Dalit background coupled with his trenchant criticism of the BJP on issues concerning the Scheduled Castes, a community the party has been wooing, may hurt it in a state where a likely alliance of the Samajwadi Party and Bahujan Samaj Party threatens to derail its prospect.
The BJP had swept the Uttar Pradesh, the largest state in terms of population and which sends 80 MPs to the Lok Sabha, in 2014 winning 71 seats.
The MP from Bahraich chose to resign on the death anniversary of Dalit icon B R Ambedkar, claiming that she wanted the Constitution implemented in letter and spirit.
"Desh ke chowikdar ki pehredari mein, sansadhono ki chori karai ja rahi hai (the country's resources are being looted under the watch of the country's watchman)," she said in a derisive reference to Prime Minister Narendra Modi.
The BJP has asserted that it would fetch more than 50 per cent votes in the state in 2019, making any unity among opposition parties inconsequential.
Read: Kushwaha declares 'war' on BJP, vague on split with NDA