Kumar, 71, who earlier in the day submitted his resignation as the chief minister heading the NDA coalition and has also submitted a list of 164 MLAs to Governor Phagu Chauhan who will decide when the oath-taking can take place. The Mahagathbandhan needs the magic figure of 122 to get majority in the state Assembly which has an effective strength of 242.?

The new development has become a symbol of the power of regional parties and a reminder that the BJP is not invincible.?

JD(U)-RJD - Who gets what?

RJD's leader Tejashwi Yadav will be the deputy chief minister and the new cabinet will have representatives from the RJD and Congress besides JD(U), according to sources. The Left parties are likely to give outside support to the new government "retaining their independent identity".

Kumar and Tejashwi Yadav will be sworn in as the Chief Minister and Deputy CM respectively at 2 pm on Wednesday in Raj Bhavan.

Nitish Kumar is likely to retain the all-important Home portfolio, while the RJD may get most of the departments that were previously with the BJP, as per PTI.

The new cabinet is likely to have “35 members or more”, drawn from Kumar’s JD(U), the RJD and the Congress.

Kumar, who is being commended by opposition parties for joining the “anti-BJP camp”, also had a telephonic talk with Congress president Sonia Gandhi over the political situation.

RJD to get lion's share

According to broader contours of the power sharing formula, the RJD will have the largest number of ministers, in recognition of the fact that it has a higher number of MLAs.

There is a likelihood of only Kumar and Tejashwi Yadav taking oath in the afternoon, since Governor Phagu Chauhan has pressing engagements and needs to travel, while remaining members will sworn in a cabinet expansion exercise later.

“The JD(U) is likely to have 13 ministers, the RJD has settled for 16. The Congress will be given four berths, while former chief minister Jitan Ram Manjhi’s HAM will have one member in the cabinet,” the source said.

A broad understanding is said to have been reached among the alliance partners on the names, barring the Congress, which needs the same to be approved by the party high command in Delhi.

The JD(U) is likely to reinstate as many of its ministers as possible from the previous cabinet, which was disbanded on Tuesday night vide a notification issued by the chief secretary.

Kumar himself will be keeping Home, which helps him have a control over the police. He is likely to also keep the departments related to welfare of extremely backward castes and minorities, which form his core constituency.

The RJD has prepared a list of names and shared it with party supremo Lalu Prasad for approval. While Tejashwi Yadav is certain to become the deputy CM, it is not yet decided which portfolios he will keep.

The in-principle decision to hand over BJP’s portfolios to RJD implies that it will get some key ones like health and road construction department, the source added

The Assembly Speaker will be selected from the RJD. As per reports, other Opposition parties including the Congress and the Left will also participate in the new government under Nitish Kumar as CM. ?The Governor, who met with both Nitish Kumar and Tejaswi Yadav on Tuesday, will play key role in deciding who gets what.?

Kumar told newspersons outside the Raj Bhavan on Tuesday, “It was decided at the party meeting that we quit the NDA. I have, therefore, resigned as the NDA’s Chief Minister”.

The changes occurred after weeks of simmering tension between the JD(U) and BJP over a host of issues including caste census, population control and the ‘Agnipath’ defence recruitment scheme and a tiff over the continuation of Kumar’s former confidante RCP Singh as a central cabinet minister. The differences culminated in a meeting of all JD(U) MPs and MLAs huddled in conference at the chief minister’s residence.

The decision they took was to quit the NDA and join hands with the Mahagathbandhan which it had spurned five years back in 2017. The CM is understood to have told party legislators and MPs that he had been driven against the wall by the BJP which tried to weaken his JD(U), first by propping up Chirag Paswan’s rebellion and later through the party’s former national president RCP Singh.

A new chapter in regional politics

Besides upsetting political calculations, the move is seen as significant as it diminishes the clout of the BJP in a key state in the Hindi-speaking heartland from where most of its legislators come ahead of the 2024 general elections, which pundits expect it to otherwise win.

This is not the first time that Nitish has dumped his alliance partners. In 2013, Nitish walked out of the NDA after Narendra Modi became the coalition's Prime Ministerial candidate. He again ditched his coalition with the RJD-Congress combine in 2017 to walk back into the NDA camp.

“Nitish’s move today is a new chapter in one form of federalisation of politics (where regional parties are taking control of states), while Maharashtra where BJP formed a coalition government (earlier this year after the Shiv Sena broke up) is one form of centralization of politics,” said Ranabir Samaddar, well-known political scientist and former professor of Maulana Azad Institute of Asian Studies.

The question of whether Kumar’s startling political moves on Tuesday will have repercussions on national politics and whether the opposition will try to build him up as a rival to Modi is of course a question which remains up in the air, to be answered in the future.

??How BJP reacted

The BJP on Tuesday reacted angrily, accusing Bihar Chief Minister Nitish Kumar of "insulting and betraying" people's mandate while blaming his prime ministerial ambition for the JD(U)'s decision to walk out of the NDA.

The party’s leaders also threw the jibe "Paltu Ram" (one who keeps changing sides), first used by Rashtriya Janata Dal supremo Lalu Prasad Yadav for Kumar, at the Janata Dal (United) leader and rejected claims that their party had tried undermining him.

"Despite having fewer seats, we made him (Kumar) chief minister. He has deceived the people twice. He is suffering from arrogance," Ashwini Choubey, BJP‘s central minister said.

Asked about Kumar's tie-up with the RJD, Choubey said, "Vinash kale vipreet buddhi" (when doom approaches, one loses wisdom).

(With inputs from PTI)