If Sonia Gandhi is known for her family, the political dynasty that helped shape modern India, Manmohan Singh (search) is defined by his policies.

A respected Oxford-educated economist reported to be Gandhi's choice to become prime minister, the 71-year-old Singh was the architect of the economic policies that turned India from a socialist behemoth to a regional economic power.

On Tuesday, reports that Singh could be the next prime minister helped send the country's stock markets soaring, just a day after suffering their worst-ever losses.

"When the markets got a whiff that Sonia may not be prime minister that was the biggest kick for the markets," said Sindhu Sameer, at Bombay-based Batlivala & Karani Securities. "If Sonia is out, then Manmohan is in and he is the poster boy of India's reforms."

Singh, a soft-spoken Sikh (search) known for his penchant for light blue turbans, would be the first member of an Indian religious minority to be prime minister. While all of India's prime ministers have been Hindus, most — like Singh — also were staunch secularists.

A technocrat who spent years in various government posts and in the International Monetary Fund (search), Singh was plucked from relative obscurity in 1991 to be finance minister.

From 1991 until 1996, when Congress lost power, the man long known for cautiousness brought about the most wide-ranging changes in India's financial system since independence from Britain in 1947.

"The country is on the edge of a precipice ... and there is no time to lose," he told Parliament in 1991, when the economy was badly stalled.

He announced a series of sweeping reforms: slashing subsidies, partial privatization of state-run companies and inviting foreign investment.

Perhaps most importantly, he ended the "license raj," the regulations that tied businesses into bureaucratic knots by forcing them to get government approval for nearly any decision.

In a country accustomed to Soviet-style economic planning, it marked a revolution.

But while he is a fierce proponent of economic liberalization, Singh also believes the market can't be counted on to help India's poorest, and that policies creating "growth with a human face" were needed.

In this week's political confusion, his role remains unclear.

The Congress scored a stunning victory last week over India's Hindu nationalist-led alliance, putting them in position to form a new coalition government.

Gandhi, the Italian-born widow of former Prime Minister Rajiv Gandhi and head of India's most powerful dynasty, had been expected to take the top office.

But trouble began immediately. A furor among Hindu nationalists erupted over her foreign birth. Stock markets plunged amid fears that her leftist backers would reverse years of business-friendly policies.

Congress officials also said her grown children feared for the safety of a woman whose husband and mother-in-law, Prime Minister Indira Gandhi, were both assassinated.

"I humbly decline the post," she told Congress members Tuesday, insisting she wouldn't reconsider.

She did not nominate anyone for the post, but Singh sat next to her as she listened to other party officials.

On Tuesday afternoon, when word leaked out that Gandhi did not want the top post, television reports quoted unidentified Congress leaders as saying Singh was her candidate.

Raised in a family of subsistence farmers, Singh went from small-town Punjab to a scholarship at Oxford and a Ph.D. in economics.

A quiet intellectual with oversized glasses, Singh is seen as a deeply honest man in a country where politics is often tainted by corruption. And where Gandhi's children are political celebrities, Singh's stay-at-home wife and three daughters keep well out of the spotlight.

As share prices plummeted Monday, it was Singh who Congress had plead for calm, promising "our policies will be pro-growth, pro-investment and pro-savings."

Few dispute he's had enormous influence.

By 2004, India's economy, which had crept along for decades, was racing at more than 8 percent.

But as the outgoing government learned last week when its campaign of "Shining India" failed miserably with voters, India's economic miracle has left many untouched.

While per capita income had climbed from $370 in 1999 to $480 by last year, tens of millions of Indians still live on less than $1 a day.