Stunning her supporters, Sonia Gandhi announced Tuesday she would "humbly decline" to be the next prime minister of India, sidestepping Hindu nationalist outrage over the prospect of a foreign-born woman leading the nation.

Gandhi, an Italian who became an Indian citizen 21 years ago when she married former Prime Minister Rajiv Gandhi, did not say whom she would nominate for the post. The favorite appeared to be Manmohan Singh, the architect of India's economic liberalization program during the last Congress-led government from 1991 to 1996.

"The post of prime minister has not been my aim," Gandhi told newly elected Congress party members in Parliament. "I was always certain that if ever I found myself in the position I am in today, I would follow my inner voice. I humbly decline the post."

Gandhi's Congress party and allies trounced the Hindu-nationalist party of Prime Minister Atal Bihari Vajpayee and his Democratic National Alliance in national elections that ended last week. They were swept to power by millions of impoverished Indians angered over being left out of the country's economic boom.

As head of the party, Gandhi had been expected to become prime minister. But she would likely have led a coalition government dependent on the outside support of two communist parties, who oppose continuing economic reforms such as privatizing state-run companies.

That prospect spooked investors and caused financial markets to tumble Monday, when the Bombay Stock Exchange registered its biggest drop in its 129-year history.

The benchmark index rose again Tuesday on news that Singh could be the new Congress party candidate for prime minister, though it was unclear how his coalition would be any different from the one Gandhi might have led.

But the new Congress party lawmakers shouted and pleaded with Gandhi to change her mind, and she had to stop several times to get the audience to quiet down. It then passed a resolution calling on her to reconsider.

Her voice quavered, after having listened for two hours to the new members of Parliament: "I have listened to your views, your pain, your anguish at the decision I have taken. I am aware I am causing anguish to you also, but I think you should trust me, allow me to take my decision."

Gandhi, 57, will remain president of the party, and will likely exert a strong influence on the government. If she had accepted the post, she would have been the fourth member of the fabled Nehru-Gandhi dynasty to be prime minister.

Jyoti Basu, a senior leader of the Communist Party of India-Marxist and a Congress party ally, said Gandhi's children did not want her to take the post. "Rahul and Priyanka said, `We have lost our father, we don't want to lose our mother as well,' " he said.

Gandhi's husband and mother-in-law were past prime ministers who were both assassinated. Rajiv Gandhi was killed by a suicide bomber in 1991, and Indira Gandhi was shot to death by her own bodyguards in 1984.

"This is a woman whose husband was killed by terrorists, a woman whose mother-in-law died of gunshot wounds. Of course, there are security concerns," said Jayanti Natarajan, senior Congress party leader.

Members of the Vajpayee's Hindu-nationalist Bharatiya Janata Party had demonstrated against the possibility of a foreign-born prime minister and pledged to boycott Gandhi's swearing in ceremony if she were named leader.

They said they were delighted with Gandhi's decision.

Gandhi was born into a Roman Catholic family but refuses to discuss her religion. Singh, the likely prime minister, is a Sikh.

Gandhi's announcement in the massive, colonial-era Parliament building was attended by 145 newly elected lawmakers from her Congress party as well as her children Rahul and Priyanka.

"It is my inner voice, my conscience," she said. "My responsibility at this critical time is to provide India with a secular government that is strong and stable."

After the announcement, a string of Congress lawmakers lined up to make speeches, pleading with Gandhi to reconsider.

Renuka Choudhury, who was close to tears, told Gandhi it was the party's desire "that you continue to lead us, because it is the need of the hour, not just for women, not just for children, but as a human being who has upheld the finest tradition of what it means to be an Indian."

But close family friend and Gandhi media adviser, Rajiv Desai, said Gandhi never intended to become prime minister but fought to put a secular government back into power.