Manmohan first full-term PM after Nehru to return to office

Nehru, independent India's first prime minister, led the Congress to victory in the 1951, 1957 and 1962 Lok Sabha elections.
Nehru died in office in May 1964 and Lal Bahadur Shastri became the prime minister. He too died in office in January 1966 after signing the Tashkent Accord on restoring sub-continental peace after the 1965 India-Pakistan war.

Nehru's daughter Indira Gandhi, who was then the information and broadcasting minister, became the prime minister and led the Congress to victory in the 1967 elections, albeit with reduced numbers.
Gandhi called elections a year early in 1971 and won a decisive mandate. Four years later, fighting off an opposition onslaught for her resignation after an adverse court verdict holding her guilty of electoral malpractices, she declared an emergency in 1975, due to which the elections which were due in 1976, were not held.

Indira Gandhi lifted the emergency in 1977 and called general elections that saw a conglomeration of disparate parties under the Janata Party umbrella being swept to power.
That experiment lasted a little over two years and Indira Gandhi led the Congress to victory in the 1980 elections.
Indira Gandhi was assassinated in October 1984 and her son Rajiv Gandhi became the prime minister. He called early elections the same year that saw the Congress being returned with a thumping majority.
The Congress, however, lost power in the 1989 elections largely due to the taint of the Bofors arms purchase scandal. V.P. Singh became the prime minister of a Janata Dal government that had outside support from the Left and the Bharatiya Janata Party (BJP).
However, the tensions generated over the 'Rath Yatra' undertaken by BJP leader L.K. Advani saw the party pulling out its support, which led to the collapse of the government.
The Congress then propped up a dispensation headed by Chandra Shekhar but pulled out after a little over 100 days, accusing the government of spying on Rajiv Gandhi.
Elections were called early in 1991, Rajiv Gandhi was assassinated while on the campaign trail and the Congress rode to power on a huge sympathy wave.
P.V. Narasimha Rao became the prime minister and served a full term but the corruption taint again saw the Congress losing power in the 1996 elections.
The BJP emerged as the single largest party and Atal Bihari Vajpayee became the prime minister, but the government lasted only 13 days as it could not cobble together the required numbers in the Lok Sabha.
A United Front coalition then assumed office, first with H.D. Deve Gowda and then I.K. Gujral as the prime minister.
Not unexpectedly, the coalition experiment lasted just two years and elections were called in 1998.
Atal Bihari Vajpayee returned as prime minister to head a BJP-led coalition that collapsed a year later. The BJP, however, retained power in the 1999 elections.

Riding what it believed was a popularity wave prompted by its "India Shining" campaign, the BJP called elections a few months early in 2004 but faced the mortification of being voted out.
Manmohan Singh then became the prime minister for the first time - and returned to power Saturday.