New Delhi/IBNS, April 10 -- A major power shift in Bihar's ruling coalition is imminent as Janata Dal (United) chief Nitish Kumar took oath as a Rajya Sabha MP, succeeding his long tenure as Chief Minister of the eastern state.

Kumar's oath was administered by Rajya Sabha Chairman C. P. Radhakrishnan at a brief ceremony held in his chamber.

Last month, Nitish Kumar resigned as Bihar Chief Minister after being elected to the Rajya Sabha.

Under constitutional provisions, he was required to relinquish his membership in the state legislature within 14 days of entering Parliament, as one cannot simultaneously hold positions in both.

At 75, Nitish Kumar is Bihar's longest-serving Chief Minister, having taken oath a record 10 times.

Over th...