With a commitment to good governance and socialist principles, the soft spoken Nitish Kumar led his Janata Dal-United (JD-U) and its then ally, the Bharatiya Janata Party (BJP), to a sweeping election victory in one of India's most populous and politically key states in both 2005 and 2010, displacing his one-time mentor Lalu Prasad.
Due to Nitish Kumar's vision and hard work, a lawless, under-developed 'BIMARU' state was now in the news for development, high growth rate and improved law and order situation.
"It was the technocrat (engineer) in him that reflected in his bid to develop Bihar and Nitish Kumar became a 'vikas purush' (man of development). Even his critics agree that he has been trying hard for a turnaround of the state," said octogenarian Bhola Prasad Singh, a veteran socialist leader and a relative of Nitish Kumar.
For one who for years seemed to work under the shadow of the more vocal and more charismatic Lalu Prasad, Nitish Kumar could emerge as a leader in his own right only after he broke away to chart an independent course in the mid-1990s.
His first stint in power in Patna was short lived. Becoming chief minister for the first time March 3, 2000 with the support of half a dozen 'bahubalis' (criminals-turned-politicians), he had to resign within a week after failing to prove his majority.
Five years later, he was back in the saddle, thanks to an alliance with the BJP, a party he had courted since 1996 but whose Hindutva politics he strongly rejected.
It was his different stand on this issue that he claimed had forced him to end the JD-U's 17-year-old alliance with the BJP last year after it chose Gujarat Chief Minister Narendra Modi as its face for the 2014 polls.
But the break-up proved costly in the general elections, with the JD-U reduced to two seats out of the state's 40.
A day after the results came out, Nitish Kumar accepted responsibility for the debacle and put in his papers.
As chief minister, Nitish Kumar, a man of few words, went about rebuilding a Bihar that had universally come to be identified with bad politics, poor governance and low quality of life.
Without noise and bluster, he re-laid roads that had virtually ceased to exist, built 12,000 bridges and completed long delayed infrastructure projects, appointed over two lakh school teachers to rebuild the shattered educational system and ensured that doctors attended health centres.
Most importantly, he cracked down on criminals and gangsters with strong links to politics. He ordered speedy trials and over 80,000 criminals, many of them politicians, were convicted.
In no time, Bihar's notorious crime rate dropped, so much so that young women began to venture out at night in cities like Patna.
But what won Nitish Kumar his popularity was the decision to give away bicycles to thousands of girls so that they could travel to their educational institutions without any hassle. Later his government announced it will provide sanitary napkins to girls.
"Nitish Kumar changed the face of Bihar as now one could spot girls riding bicycles, and people fearlessly moving around till late night. It was not the situation some years back," said Vashisht Narain Singh, a JD-U leader close to Nitish Kumar for over two decades.
Seeking to change the face of Bihar, he succeeded to a large extent with limited resources though his demand for a special category status for Bihar failed to materialise.
Like Lalu Prasad, Nitish Kumar was a product of Bihar's student movement of the 1970s. He still considers himself a socialist at heart.
A teetotaller who detests tobacco, the widower has a son. But unlike Lalu Prasad, he keeps his family away from the limelight with neither son Nishant Kumar nor his elder brother in politics.
Born in 1951, Nitish Kumar was elected to the Bihar assembly in 1985 for the first time. He became president of the Yuva Lok Dal in 1987 and secretary general of the then undivided Janata Dal two years later.
He got elected to the Lok Sabha for the first time in 1989 and went on to win five parliamentary elections from Bihar.
A minister of state in the V.P. Singh government, he became railway minister in the Atal Bihari Vajpayee government but resigned when a train disaster claimed the lives of about 250 people. He returned to the cabinet as minister for surface transport and agriculture.
But all through his innings in Delhi, he never lost sight of his ultimate goal: govern Bihar to develop it with his pet agenda "development with justice".