But sizzling temperatures kept people indoors and only 40 percent of some one million registered voters turned out in her home constituency of Rae Bareli in Uttar Pradesh state, electoral officials announced.

"It's the heat that kept people indoors," a Congress party spokesman said as the temperature touched 42 degrees Celsius (107 degrees Fahrenheit) in Rae Bareli, a bastion of India's Nehru-Gandhi dynasty.

The voting was marred by a solitary incident in which unidentified gunmen shot at a rival political activist, police said.

The Italian-born 59-year-old widow of assassinated former prime minister Rajiv Gandhi had won the seat in 2004 parliamentary elections that brought her party to power in a coalition government.

Gandhi resigned on March 23 after opposition charges that she was wrongfully holding two salaried posts, which is banned under the constitution for an MP. Her action took the sting out of a political storm that had threatened to engulf her party.

Her daughter Priyanka and brother Rahul, Gandhi's political heir-apparent, spearheaded a publicity blitz for their mother in advance of the by-election.

"Of course she will win," Priyanka told reporters.

Only the margin of victory over her main challenger, Vinay Katiyar of the Hindu nationalist Bharatiya Janata Party, has been open to debate.

"It's an open-and-shut case," said political analyst Mahesh Rangarajan.

"What we have to see is the size of the majority -- she won by 240,000 votes last time (2004) -- we have to see if it goes up or down," Rangarajan said.

Gandhi's victory has always been considered a foregone conclusion, agreed Rashid Kidwai, Sonia's official biographer. But he said the victory would be more of a symbol for Congress.

"A landslide win is not expected to put a stop to the Congress party's declining fortunes" in India's most populous state, with 80 members of parliament, he said.

Also Monday millions of Indians voted in the final phase of elections to several state assemblies, which are seen as a referendum on the federal Congress-led government as it approaches two years in power.

The Marxist bastion of West Bengal, the southern state of Tamil Nadu and the union territory of Pondicherry saw balloting Monday.

Poll officials announced a 70-percent turnout in Monday's final leg of the five-phased balloting in West Bengal, a figure widely seen as a clear verdict in support of the state's ruling Marxists.

More than eight million people were eligible to vote for 306 candidates in the state, where a communist government has been in power since 1977.

Voting in northeastern Assam and the southern state of Kerala is complete and results for all five states will be announced on May 11.

The Marxist-led left-leaning parties were expected to return to power in West Bengal and to defeat the ruling Congress-led coalition in Kerala, opinion polls said.

In Tamil Nadu, the two main regional fronts were locked in a fierce competition to woo voters, promising gold for women planning to marry and computers for students who passed certain examinations.

Related Links
-