While prima facie it might seem to be a clash of two strong personalities i.e. Modi and Kumar, there is much more to the split than that.

The Nitish Kumar led Janata Dal (United) (JD-U) ended its 17 year old alliance with the Bhartiya Janata Party (BJP) on Sunday afternoon.

This was on account of the fact that the BJP has or more less declared Narendra Modi as its prime ministerial candidate, something which did not go down well with Kumar and JD(U).

While prima facie it might seem to be a clash of two strong personalities i.e. Modi and Kumar, there is much more to the split than that. In order to understand the real reason behind the split one has to understand the caste politics of Bihar in its most basic form.

Nitish Kumar belongs to the kurmi caste which is numerically too small to help him win elections. At the same time the people belonging to the caste are geographically concentrated and not spread through the state. The kurmis form around 3.5 percent of the state's population. In comparison, the yadavs, who back Lalu Prasad Yadav, Nitish's biggest political rival in the state, form 11.7 percent of the population.

Given this factor, over the years Nitish has had to chip away at votes from other castes. This has included wooing the mahadalits (primarily the non Paswan schedule castes, which included Dalits other than the Dusadh, Chamar, Pasi and Dhobi castes) and the extremely backward classes or the EBCs (primarily the non yadav backward classes). The EBCs form 32 percent of the state's population but had only a 5 percent representation in the state assembly.

It has also included wooing the backward caste Muslims i.e. the pasmandas. This was what helped Nitish Kumar break Lalu Prasad Yadav's M-Y or Muslim-Yadav formula. The M-Y formula was the main reason behind Lalu winning successive elections despite governance in Bihar almost coming to a standstill. Muslims form 16-17 percent of the population in the state which is much more than 9.9 percent nationally.

What is interesting here is that even though Lalu Yadav successfully wooed the Muslims, when it came to distributing goodies he concentrated on the upper caste Muslims i.e. the ashrafs.

Manjur Ali studies this phenomenon in a research paper titled Politics of 'Pasmanda' Muslims : A Case Study of Bihar. As he writes,

“Lalu Prasad Yadav in the name of M-Y (Muslim-Yadav) alliance has promoted the FM-Y (Forward Muslim-Yadav) alliance, where major benefits were cornered by Ashraf Muslims in the name of the community... Unemployment, poverty and apathy of the state towards their problems were never raised by the Bihar Ashraf political elites ..The RJD made fourteen Muslims MLCs, out of which twelve were upper-caste Muslims. Again, there were seven appointments made for the post of Vice Chancellor, all from upper castes. Similarly, appointment to government posts like teachers, posts in the police department and in minority institutions were allotted to the sharif people. In turn, Lalu received blessings from religious leaders belonging to the upper castes for his electoral victory.”

Nitish Kumar was sympathetic to the cause of backward caste Muslims while Lalu Yadav took Muslim support for granted. On 8 October 2005, seven pasmanda political parties issued a clarion call to defeat Lalu Yadav's Rashtriya Janata Dal (RJD) in the state assembly elections. Slogans like ‘Vote hamara fatwa tumhara, nahi chalega’ (your dictate on our vote will not work) and ‘jo pasmanda ki baat karega, wahi Bihar pe raaj karega’ (those who concede the demand of Pasmanda will rule Bihar) became the order of the day.

This split in the Muslim vote along with other caste alliances, helped Nitish Kumar become the Chief Minister of Bihar in November 2005. In fact he first realised the power of the Muslim vote in 2004. The BJP-JD(U) alliance won just 11 out of the 40 Lok Sabha seats in the state. This was despite the fact that the people of the state were fed up with the misrule of Lalu Yadav and Rabri Devi. But in reality the Muslims had not voted for the BJP-JD(U) alliance because they were punishing it for the Gujarat riots of 2002.

In the state assembly elections of 2005, Nitish Kumar wooed the pasmanda Muslims and did not allow Narendra Modi to campaign in Bihar. The JD(U)-BJP alliance did very well as a result, winning 143 out of the 243 seats in the state assembly. This anti Modi stand continued and the alliance did very well in the state in the 2009 Lok Sabha elections and 2010 state assembly elections as well. He also ensured that Modi did not campaign in these elections. So Nitish Kumar has seen his anti-Modi stand reap electoral benefits in the past.

Hence, any direct association with a BJP that has Narendra Modi at the top would clearly have cost Kumar the pasmanda votes and helped his bete noire Lalu Yadav resurrect his M-Y formula. In fact, in the recently concluded Lok Sabha by-election in Mahrajganj, the RJD candidate won by 1.37 lakh votes. The worrying thing here for Kumar was that Muslims seem to have voted for the RJD enmasse. This was the final nail in the coffin for the BJP-JD(U) alliance.

Critics of Nitish Kumar have repeatedly asked why he continued in the NDA government in Delhi after the 2002 Gujarat riots. "If he had a problem, he should have quit then. Why wait for 11 years?" they ask. While this seems like a valid point that is not how things work in politics.

In 2002, and until very recently, Modi was nowhere in the national scheme of things for the BJP. Hence, there was no direct association between Nitish Kumar and Modi. But now with Modi practically the BJP's prime ministerial candidate, the Muslim vote would have moved enmasse to RJD, which is something that Kumar could ill-afford. In the past Nitish managed to keep Modi away from Bihar, but now with Modi in this position, that would not have been possible.

That's one part of the story. The caste alliances that Nitish Kumar built were one reason behind the success of the BJP-JD(U) alliance. Nevertheless the alliance was also helped by the upper caste vote that the BJP brought with it. The Brahmins, Rajputs, Bhumihars and Kayasthas, form the upper castes and account for around 16 percent of votes in Bihar.

The upper castes formed the icing on the cake. In fact, the JD(U) leader and former convener of NDA, Sharad Yadav, admitted as much when he said after the 2005 win: “We had the masses with us but I am not sure we would have won such a landslide without the BJP. Although some JD(U) members wanted to break from BJP, we realised that it was the BJP which had the support system – the upper-caste dominated press, bureaucracy and judiciary. Though Nitish led from the front, the BJP played its part in this win.”

Manish K Jha and Pushpendra summarise the situation very well in their 2012 research paper Governing Caste and Managing Conflicts Bihar, 1990-2011:

“Nitish Kumar had assiduously worked to bring together a coalition of Kurmis, Koeris, EBCs, lower Muslims (Pasmanda) and Mahadalits. and the upper-caste and business-community support-base of his party’s coalition partner, BJP. Finally, in November 2005 assembly elections, EBCs consolidated their votes in alliance with lower caste Muslims and upper castes and RJD regime was replaced by the JD(U)-BJP coalition.”

In a state as feudal as Bihar, for any party the support of the upper castes is a huge help. What the BJP also brings with itself is the RSS cadre, which is a huge help during the election process, from campaigning to manning booths to having the right electoral agents at the right booths. This is something that Nitish would have realised during the recent Maharajganj Lok Sabha poll.

One possibility for Nitish is to align with the Congress to make up for the loss of the votes that BJP brought in. The Congress has already started sending feelers regarding an alliance. There are two problems with this approach. The first problem is that the Congress is more or less dead in the state. Hence, any alliance between the two parties is going to benefit the Congress more than the JD(U).

The second problem is that the Congress already has an alliance with Lalu Yadav's RJD. And aligning with the Lalu won't go well with the political plank of development that Nitish has built and also delivered on. Any political leader who stands for economic development can't be seen aligning with Lalu Yadav, the very antithesis of development. But as they say funnier things have happened in politics.

Given these reasons, Nitish Kumar and JD(U) will be worse off after the split with the BJP, but only slightly. Nitish's bigger interest here seems to hold back Lalu Yadav from resurrecting his MY alliance and from the way things stand here, he should be successful at that.

As far as the BJP is concerned it will continue to get the support of the upper castes in the state. But that in itself will not be enough to win a substantial number of the 40 Lok Sabha seats. In the current Lok Sabha, the BJP-JD(U) alliance had 32 seats from the state.

Also, it is worth remembering that Hindutva was never really a big issue in Bihar. Even after Lalu Yadav arrested Lal Krishna Advani during the course of his 1990 Rath Yatra, the state continued to remain peaceful.

So the BJP's attempts to resurrect this issue (as it is plans to in Uttar Pradesh by appointing Modi's lieutenant Amit Shah as in-charge of the party in the state) won't really work in Bihar. Given these reasons, it will be difficult for the party to win more than 10 Lok Sabha seats from the state, on its own.

Hence, Modi will have to work more magic in other states so as to ensure that the party wins enough seats on its own so that potential allies are attracted to it at least after the elections.

(Vivek Kaul is a writer. He tweets @kaul_vivek)