With Bihar Chief Minister Nitish Kumar announcing he will move to the Rajya Sabha, the BJP has finally stamped its authority within the NDA in the state. A junior partner in the alliance for decades, the BJP will for the first time have its own CM in the state. Kumar’s exit — the JD(U) has won fewer seats than the BJP in two successive Assembly elections — also has the potential to significantly realign Bihar politics.The shift in the NDA’s internal balance has been years in the making. While the Vajpayee-Advani era coalition politics helped the BJP build its base in Bihar, the Modi era has seen the party nurture larger ambitions under a more centralised ideological and organisational leadership.AdvertisementSigns of the transition were visible even before last year’s Assembly elections. The JD(U) agreed to contest an equal number of seats with the BJP — historically it had contested more — conceded a substantial share to the LJP (Ram Vilas) of Chirag Paswan, and after the government was formed, gave up the state Home portfolio that Nitish had always retained.Yet, as the principal pole of politics in Bihar now, the BJP faces challenges of its own: producing a credible local leadership capable of filling Nitish’s large boots and expanding its social base beyond its traditional support among upper castes, Banias, and a section of OBCs.Read | As Nitish Kumar moves to RS, next Bihar CM likely from BJP: A look at the front-runnersCoalition compulsion to dominanceAdvertisementIn the Vajpayee years, the BJP’s Bihar strategy was constrained by the NDA’s broader “coalition dharma”. Regional parties born of Mandal politics — from the JD(U) in Bihar to its variants elsewhere — possessed both ideological veto power and seat-sharing leverage. The BJP needed their backward-caste anchors to counter the Congress and regional social justice parties and therefore accepted a junior or co-equal role.The Modi era altered that hierarchy across the Hindi heartland. A sharper Hindutva nationalism, combined with welfare delivery and leadership-centric messaging, began cutting across sub-caste boundaries. This allowed the BJP to overshadow or subordinate allies in states such as Uttar Pradesh, Maharashtra, Karnataka, and Haryana.In Bihar too, the party’s long-term objective shifted from being a reliable junior partner to becoming the alliance’s hegemonic pole: retain regional allies when useful, but ensure the BJP’s vote base, organisation and leadership bench are strong enough that no partner can credibly threaten it.Slow and steadyThrough the 2000s, the BJP largely rode on Nitish Kumar’s political strength. In October 2005, the JD(U)-BJP alliance ended RJD rule with JD(U) winning 88 seats to the BJP’s 55. In 2010, the JD(U) again led with 115 seats while the BJP had 91, giving the alliance 206 seats in the 243-member Assembly. Nitish’s governance image and Kurmi-centred backward caste base defined the coalition, while the BJP brought upper-caste, urban, and trader votes.The inflection came in 2014 when Nitish broke with the NDA over Narendra Modi and contested the Lok Sabha elections with the CPI. The JD(U)-CPI combine won just two of Bihar’s 40 seats with about 16% vote share. In contrast, the BJP-led NDA swept 31 seats, with the BJP alone winning 22 and securing nearly 30% vote share.The 2015 Assembly election became the clearest test of the BJP’s independent strength. Fighting without JD(U), the BJP-led NDA was defeated by the Mahagathbandhan. Yet, the BJP emerged as the single-largest party by vote share, registerin 24.4% vote share and a tally of 53 seats, compared with RJD’s 18.4% and JD(U)’s 16.8%. That demonstrated the BJP’s independent pull but also its inability to assemble a winning social coalition on its own.When Nitish returned to the NDA in 2017, the BJP stopped deferring. In the 2020 Assembly polls, it overtook the JD(U) within the ruling alliance: the BJP won 74 seats and 19.46% vote share against JD(U)’s 43 seats and 15.39%, though Nitish remained the CM.The shift was aided by Chirag Paswan-led LJP contesting separately and fielding candidates only against the JD(U). Many in the JD(U) believe this was done with the BJP’s tacit support to cut Nitish down to size.The episode eventually triggered another split in the NDA, with Kumar returning to the RJD-led alliance before rejoining the BJP ahead of the Lok Sabha elections amid speculation about his health and the future of his party.By 2025, the political logic had become clear. The NDA swept 202 seats, with the BJP winning 89 and JD(U) 85. Yet the BJP — not the JD(U) — emerged as the alliance’s pivot for leadership decisions and cabinet formation. For the first time, the state Home portfolio, long retained by Nitish Kumar, went to the BJP.Organisation, outreach, and limitsThe BJP’s rise has been driven not only by alliance politics but also by deliberate organisational expansion and social outreach. Over the past decade, the party has worked to graft non-Yadav OBCs and Extremely Backward Classes (EBCs) onto its traditional upper-caste base through targeted ticket distribution and leadership promotion. In Bihar, this has meant elevating leaders such as Samrat Chaudhary (Koeri/Kushwaha) and Nityanand Rai (Yadav).At the same time, the party built a formidable organisational network under Amit Shah, expanding booth-level structures, deploying full-time pracharaks, and running intensive rural campaigns. Combined with the financial and media advantages of being in power at the Centre, this has given the BJP resources that regional parties such as JD(U) and RJD struggle to match.Yet, the BJP’s Bihar numbers also reveal its limits. The party has yet to produce a leader who commands the kind of cross-caste appeal that Nitish once did. Many of its prominent OBC faces are imports from social justice parties rather than leaders groomed within the BJP’s ideological ecosystem.The 2015 Assembly election remains the clearest indicator of this ceiling. With 24.4% vote share and 53 seats — and the NDA tally reaching only 58 with allies — the BJP demonstrated it could match or exceed any single party’s vote share, but not yet build a broad enough coalition to secure a majority on its own.Subsequent results reinforce this point. In 2020, the NDA scraped a majority largely because JD(U) remained part of the alliance. In 2025, the BJP became the largest party in the Assembly but still trailed the RJD in statewide vote share: RJD at 23%, BJP at 20.08%, and JD(U) at 19.25%.“It is true we haven’t groomed local OBC leaders. But power has this great ability to shape leaders. Now that we will be in pole position in the government, leaders will rise,” said a BJP leader in Bihar.The JD(U) questionyou may likeIn purely organisational and arithmetic terms, the BJP’s cleanest path to undisputed dominance would be a merger with the JD(U). Combining the two parties’ vote shares while absorbing Kurmi-EBC networks would eliminate the only ally capable of switching sides and destabilising governments.But the costs remain significant. The JD(U)’s distinct regional identity still helps the NDA retain support among sections that may not automatically shift to a unified BJP. Absorbing the party too quickly could also concentrate anti-incumbency against the BJP and trigger internal competition over leadership and tickets.“Why should we push it? Why should we deliberately inherit the problems or the legacy of the JD(U)? In any case, as long as Nitish ji is there, this is not happening. The party might collapse on its own eventually. At that time, most JD(U) leaders will come to us,” said a BJP leader from the state.