Patna/IBNS: Janata Dal (United) supremo Nitish Kumar Sunday resigned as Bihar Chief Minister ending days of political speculation over his fifth switching of alliance in a decade.

Kumar met Bihar Governor Rajendra Arlekar this morning and handed over his resignation.

This is his eighth resignation in a political career, which saw his rise as a model of good governance before his repeated jumps across the political aisle that hit his popularity and his party JDU's electoral stature.

Speaking to reports outside the Rashtrapati Bhavan, Kumar said: "I have tendered resignation as the chief minister today. I took this decision after listening to my party's MLAs. I will now form a new alliance today," Kumar said indicating his switch to BJP.

"I tried to put up an alliance of opposition but nothing was happening there," Kumar said on the decision to ditch the opposition INDIA alliance, something that was initiated by him.

The 72-year-old met with all JD(U) legislators in the morning before resigning as the Chief Minister, only to take a fresh oath with the BJP alliance in the evening.

All BJP MLAs in Bihar have already given letters of support to Nitish Kumar.

The BJP and JD(U) have also finalised a seat-sharing agreement for the Lok Sabha election due in three months.

Nitish Kumar had hoped to be chosen as the leader of the opposition alliance. However, the allies opted for Congress chief Mallikarjun Kharge for the role after Mamata Banerjee and Arvind Kejriwal proposed his name.

The JD(U) leader was also unhappy with the Congress for assuming a "big brother" role in the alliance and causing delays in the discussions about seat-sharing.

Kumar, who is upset with Congress's indifference towards his role in the formation of the opposition INDIA bloc, lost his cool when he was targeted by RJD on Thursday.

While addressing a party event on Wednesday to mark the birth centenary of former Chief Minister Karpoori Thakur, he obliquely slammed RJD Chief Lalu Prasad for promoting his sons in politics.

The reports have sent RJD and the Congress into a huddle, with both parties holding several meetings to discuss the plan of action if Kumar exits. JD(U) was among the top parties in Opposition's INDIA bloc which aims to challenge Prime Minister Narendra Modi in the Lok Sabha polls.

In the Bihar Assembly of 243, the RJD has 79 MLAs; followed by the BJP's 78; the JD(U)'s 45' the Congress's 19, the CPI (M-L)'s 12, two each of the CPI(M) and CPI, the Hindustani Awam Morcha (Secular)'s four seats, and the AIMIM's one, plus one Independent legislator.