NEW DELHI, NOV. 6 -- Socialist Chandra Shekhar took a decisive step toward becoming India's next prime minister today after opposition leader Rajiv Gandhi announced that his party would support Shekhar's bid to lead the government.

The announcement appeared to assure Shekhar of a majority in the lower house of India's Parliament while worsening Prime Minister V.P. Singh's prospects in a confidence vote scheduled for Wednesday. Singh is now expected to lose the confidence vote overwhelmingly, ending his 11-month tenure in office and opening the way for a new government headed by Shekhar.

Shekhar, a patrician socialist who greets interviewers in a sparsely furnished room outfitted with expensive stereo equipment and a cellular telephone, engineered a split in the prime minister's governing Janata Party on Monday. An estimated 58 members of Parliament joined Shekhar to form a breakaway party, which Shekhar has dubbed the Janata Party (Socialist).

This week's maneuverings appear to have been guided more by personal animosities and ambitions than by ideology or issues. All of the leading contestants to succeed Singh as prime minister voice support for decades-old policies such as a mixed socialist economy, a strong central bureaucracy, secularism, expansive welfare programs and continued growth in defense spending.

After several days of hectic negotiations, Shekhar today persuaded former prime minister Gandhi to announce publicly that his centrist Congress Party would back Shekhar's rebel Janata Party faction. Gandhi, who led the government for five years before being repudiated in national elections nearly a year ago, still controls the parliament's largest voting block.

The announced deal between Gandhi and Shekhar must still be ratified by India's head of state, President R. Venkataraman, who can dissolve Parliament and call for new elections. But officials close to Gandhi and Shekhar who have met with Venkataraman expressed confidence today that the president would support their move to form a new government rather than call a vote.

Hundreds of people have died in caste and religious violence across India in recent weeks, and there are fears that an immediate election would exacerbate the violence. Many sitting politicians also oppose a new vote because they do not want to risk their offices so soon after the last election.

Singh's Janata Party faction was not yet ready to surrender. Singh again refused to resign before Wednesday's confidence vote and his faction today mounted a parliamentary maneuver that was evidently aimed at blocking Shekhar's faction from voting as a bloc in the lower house. The maneuver was expected to fail.

Shekhar and Singh, both former Congress Party members raised on estates in India's north, have been at loggerheads for more than a year, and Shekhar makes no apologies for his acute dislike of his rival. When Singh became prime minister last December, he bested Shekhar in an intrigue-laden Janata Party vote. Shekhar said at the time that he felt embarrassed and betrayed by the outcome.

Ever since, Shekhar has been plotting openly to defeat the prime minister. Last month, Shekhar agreed to pose for a prominent Indian magazine's cover photograph while holding a goose on his lap. The magazine's cover headline asked, "Cooking V.P.'s Goose?"

The caste and religious turmoil that had plagued Singh since he took power came to a boil last week when the prime minister chose to oppose with force an attempt by Hindu militants to build a temple on the site of a mosque in the town of Ayodhya.

Angered by the prime minister's move, which triggered mass arrests and violence, the Hindu revivalist Bharatiya Janata Party (BJP) -- the third largest party in Parliament -- withdrew its support for Singh's minority government. BJP leader L.K. Advani, who had led a march to the site of the disputed mosque, was among those arrested.

Shekhar then encouraged dissidents in Singh's party to break with the prime minister and join him in a new government. About half of the Janata Party's legislators, mainly those without prestigious cabinet posts, agreed to follow him.

If Shekhar becomes prime minister, he almost certainly will lead a minority government dependent on Gandhi's Congress Party support for its survival -- a position of weakness similar to the one that has plagued Singh during his 11 months in office.

Some Indian commentators and diplomats believe Gandhi chose to back Shekhar in the manner announced today so that he can withdraw support whenever Gandhi is fully confident that his party -- which has governed India for all but four of its 43 years of independence -- can win a new election outright.

That scenario is a familiar one in recent Indian political history. In 1977, the Janata Party defeated the Congress Party for the first time since independence. But after taking office, the party split amid personal rivalries and differences over religious issues.

A rebel Janata faction backed by the Congress Party took power in 1979, but it collapsed shortly afterward when Gandhi's mother, Indira Gandhi, withdrew her support and went to the polls, sweeping to an easy victory. The Congress Party held power for nearly a decade, until Singh's fractious Janata Party-led coalition defeated Rajiv Gandhi last year, claiming that the former prime minister was corrupt and incompetent.