Manmohan Singh is respected for his integrity, but seen by critics as soft
Derided by the opposition BJP as weak, Indian PM Manmohan Singh showed his steel by guiding Congress to another decisive election victory.
Thanking the people for renewing their faith in his government by delivering a "massive mandate", Mr Singh vowed that Congress would "rise to the occasion".
Manmohan Singh is widely regarded as the architect of the country's economic reform programme. He is the first Sikh to hold the top post.
He is also viewed as perhaps the cleanest politician in India - in contrast, observers note, to several members of his first-administration cabinet tainted by corruption charges.
A studious former academic and bureaucrat, he has kept a low profile as the leader of more than a billion Indians.
Ahead of the May-April 2009 polls, the 76-year-old was plagued by poor health, taking a six-week break after marathon heart bypass surgery.
Again not standing for the lower house - he is an upper house member - Mr Singh has still never won a popular election - he became prime minister after Congress leader Sonia Gandhi turned down the post in 2004.
The biggest triumph during his first five-year-rule was to bring India out of nuclear isolation by signing a landmark deal with the US.
But the deal came at a price - the government's communist allies withdrew support after protesting against it, and Congress had to make up the lost numbers by enlisting the support of another regional party amid charges of vote buying.
Mr Singh rose to political prominence as India's finance minister in 1991, taking over as the country was plunging into bankruptcy.
In his maiden speech he famously quoted Victor Hugo, saying that "no power on earth can stop an idea whose time has come".
That served as the launch for an ambitious and unprecedented economic reform programme.
Mr Singh slashed red tape, simplified the tax system and removed stifling controls and regulations to try to create an environment conducive to business.
The economy revived, industry picked up, inflation was checked and growth rates remained consistently high in the 1990s.
He is a strong advocate of a "mixed economy model" with an important role for government-owned companies, especially in infrastructure and agriculture.
His unexpected anointment as the finance minister capped a long and illustrious career as an academic and civil servant.
After attending the Panjab University he took a master's degree at Cambridge University and a D.Phil at Oxford.
He taught economics in universities in India and abroad, including the prestigious Delhi School of Economics and Oxford.
In his role as a technocrat, Mr Singh headed India's central bank, advised the government on managing the economy and was a governor with the International Monetary Fund (IMF) and the Asian Development Bank (ADB).
Mr Singh once told an interviewer that he was "very surprised" when he was invited to become the finance minister.
Critics have accused Manmohan Singh of being a placeman for Sonia Gandhi
"I didn't believe it. When I asked some friends of mine they said, 'You are going to become the scapegoat. You're going to fail and maybe within six months you will be out'.
"I'd held all the top civil service jobs, but here was an opportunity to play a political role, and there was an odd chance that we would make a success of it, in which case I would have a footnote in India's history," he said.
Manmohan Singh is a man acutely aware of his lack of political mass base. "It is nice to be a statesman, but in order to be a statesman in a democracy you first have to win elections," he once said.
He has never personally won a mass, popular vote, although he may claim the 2009 election serves as such. Rather, other leaders selected him.
When he was the finance minister, he derived his political capital from the then prime minister, PV Narasimha Rao.
As the prime minister, he derives it from Sonia Gandhi - one reason why he has kept his profile low.
When he tried to be elected to India's lower house, in 1999, he was defeated. He sits instead in the upper house, chosen by his own Congress party.
Even so, he has enjoyed massive popular support, not least because he was seen by many as a clean politician untouched by the taint of corruption that has run through many Indian administrations.
A consensus builder, he has found himself presiding over a coalition of sometimes difficult, assertive and potentially unruly regional coalition allies and supporters.
Mr Singh presented the US nuclear deal as the showpiece of his tenure
And though he has earned respect for his integrity and intelligence, he also has a reputation for being soft and indecisive.
In office he continued with his programme of economic reforms including debt relief for impoverished farmers and reform of the tax system in a bid to encourage growth.
However, some critics claimed that the pace of reform slowed and he failed to achieve the same momentum he had while finance minister.
As the first Sikh prime minister he made a public apology in parliament for the 1984 riots in which some 3,000 Sikhs were killed.
In his foreign policy, Mr Singh adopted the pragmatic politics pursued by his two predecessors.
He continued the peace process with Pakistan - though this process was hampered by terrorist attacks blamed on Pakistani militants, culminating in the Mumbai shootings of November 2008.
He tried to end the border dispute with China, brokering a deal to reopen the Nathula pass into Tibet which had been closed for more than 40 years.
Mr Singh increased financial support for Afghanistan and became the first Indian leader to visit the country for nearly 30 years.
His policy of strengthening ties with the US culminated in a visit to India by the then President George W Bush in 2006 and the signing of a deal giving India access to American nuclear technology.
He angered many opposition politicians by appearing to end relationships with India's oldest ally, Iran, during the confrontation over the latter's nuclear programme.
History in general will remember him for bringing India out of economic and nuclear isolation.