In politics, there are no permanent friends but only permanent interests. This adage proved true once again as Nitish Kumar yesterday took fresh oath as chief minister of India's politically key state Bihar. His party Janata Dal (United) formed a government in alliance with Bharatiya Janata Party.

Before yesterday's reunion, Kumar and Narendra Modi were bitter political foes for the last four years. A couple of years ago, Kumar had spearheaded a campaign in Bihar state assembly polls against Modi projecting the electoral battle between a “Bihari” and “Bahari” (outsider). Modi had extensively campaigned for BJP in that election. Kumar came out triumphant in that battle in alliance with Lalu Prasad Yadav's Rashtriya Janata Dal and Congress party.

The revived political friendship between BJP and Kumar-led Janata Dal (U) has thus come full circle four years after the two parties had parted ways over Kumar's strident opposition to the saffron party projecting Narendra Modi as its prime ministerial face in 2014 parliamentary polls and opened the gates for a major realignment of forces that could boost BJP in its efforts for retaining the mandate to rule India after next parliamentary polls.

 It also came a day after snapping ties with Lalu Prasad Yadav-led Rashtriya Janata Dal and Congress party in a move that could hurt the opposition's bid for a united front against Modi-led BJP in fresh general elections in 2019.

 There were early indications about Nitish Kumar's bonhomie with BJP: his open support for Modi government's scrapping of high-currency notes last year to fight black money, Indian military's surgical strike against Pakistan and Janata Dal (U)'s backing for BJP candidate Ram Nath Kovind in Presidential elections.

 66-year-old Kumar quit as chief minister on Wednesday evening citing the refusal of his deputy Tejashwi Yadav, son of Lalu, who was embroiled in a controversy following an FIR related to alleged corruption in allotment of prime land by Lalu in 2006 when Lalu was India's railway minister for construction of a hotel in Patna.

The FIR also alleged that Lalu's family, including Tejashwi, also allegedly got a prime plot of land in Patna in return for awarding tenders to a business group.

Only last week, India's Central Bureau of Investigation had conducted raids at the premises of Lalu and Misa in Delhi and Patna.

Kumar took the moral high ground that his conscience did not allow him to continue the alliance with RJD in the wake of corruption charges not only against Tejashwi but also against Lalu's wife Rabri and daughter Misa.

The coming together of BJP and Kumar's Janata Dal (United) four years after the latter had parted ways with the saffron outfit opposing Narendra Modi's projection as PM candidate in 2014 general elections, could come as a setback to Congress and rest of the opposition struggling to contain Modi's surge in a series of state-level elections in the last few months. 

The speed with which BJP rushed to the assistance of Kumar after he severed the ties with RJD that the script for the fresh alignment of forces was prepared in advance.

Soon after Kumar's resignation as chief minister last night, Narendra Modi took to his Twitter account and congratulated Kumar for joining the fight against corruption. The PM's tweets were a clear pointer to the unfolding fast-paced political drama last night. 

Secondly, BJP's highest decision-making forum -- the parliamentary board -- met in Delhi and promptly endorsed the decision to support steps to avoid mid-term elections to the Bihar legislative assembly, an euphemism to support Janata Dal (U) and share power with it in the state reviving a coalition which had worked successfully there till the year 2013.

Thirdly, BJP President Amit Shah spoke to his party colleagues in Bihar last night and a meeting of the party's legislators was held in Patna late in the night to express support to Kumar. Around the same time, Janata Dal (U) legislators also met and at midnight, a joint meeting of legislators of the two parties was held where it was decided to share power again.

Nitish Kumar's party, which had a 17-year-old alliance with BJP till 2013, was reduced to just two parliamentarians from 20 out of the total of 40 Lok Sabha seats in Bihar in 2014 parliamentary polls. Then in 2015, Kumar aligned with RJD for 2015 state legislative assembly elections and BJP suffered its first defeat under the leadership of Narendra Modi.

BJP has been concerned about its electoral prospects in Bihar as the party knows that an overarching alliance of Janata Dal (U), RJD and Congress not only in the state but also across India was tough to beat.

The manner in which the alliance in Bihar had successfully stopped BJP had raised hopes in the opposition camp that this could be replicated nationally to thwart the Modi juggernaut. By bringing Janata Dal (U) on its side in Bihar, BJP seems to have put paid to opposition expectations and undermine efforts to form a grand anti-BJP alliance for the 2019 general elections.

The coming together of BJP and Janata Dal (U) once again may help the saffron party in consolidating its position in India's two political key adjacent states — Uttar Pradesh and Bihar — which together account for 120 Lok Sabha seats. BJP is already firmly in saddle in UP where it won a landslide mandate in April this year in state legislative assembly polls. In 2014, BJP won 70 of the 80 parliamentary seats in UP, demolishing regional satraps like Mulayam Singh Yadav and Mayawati and repeated the act in assembly polls three years down the line. 

Bihar is also crucial for BJP in its quest for retaining power in 2019. BJP and its allies won 31 of the 40 parliamentary seats.

The BJP-Janata Dal (U) alliance could dent the chances of key regional parties in states joining hands with Congress to combat BJP under Modi or spur arch rivals like Mualayam Singh Yadav and Mayawati and join a “secular” alliance to try and stop BJP's dominance.