Ruling Congress party frontman Rahul Gandhi warned Saturday of an India divided by caste and creed if the Hindu nationalist opposition wins power, as campaigning ended ahead of the last round of voting in the nation's multi-stage election.

Gandhi, scion of India's most famous political dynasty, sought to muster a final show of strength in the holy Hindu city of Varanasi with the party struggling to snatch victory from the jaws of a widely forecast defeat by the Bharatiya Janata Party (BJP).

The BJP "only wants to divide people, make people fight each other", Gandhi told a rally in Varanasi, one of the last constituencies due to vote in Monday's final day of balloting.

The city has become a focus of national attention with two star candidates -- one of them Narendra Modi, a charismatic but controversial figure tipped to lead the BJP to power and become prime minister of the world's largest democracy.

The other is anti-corruption campaigner Arvind Kejriwal who vaulted to national prominence as leader of the upstart Aam Aadmi -- Common Man -- Party. Kejriwal said he was confident of "a huge majority" in the temple-studded city.

Even though Congress -- running a local candidate -- is given little chance in Varanasi, the broader national battle is between the party, which Gandhi's family has steered since India's 1947 independence, and the BJP.

The two parties engaged in a last campaign duel with Congress spokesman Abhishek Manu Singhvi deriding what the Hindu nationalists have called a "tsunami of support" for Modi as "a chimera".

"The BJP is fast discovering its estimates are nothing but guesses," Singhvi told reporters. Results of the election that began in early April will be known on Friday.

BJP leader Rajnath Singh fired back, telling a news conference voters are "eager to be rid of Congress".

Modi has been an indefatigable campaigner who travelled 300,000 kilometres (180,000 miles) in the last eight months speaking to 437 rallies, according to the BJP. In a novel move to reach out to voters, he also addressed 1,350 gatherings as a hologram, the party said.

Modi, projecting himself as an outsider who will radically overhaul India's political status quo, launched a blistering attack Saturday on the Gandhi family.

- 'Mother-son government' -

The 63-year-old mocked Gandhi and his party president mother, Sonia, as the "mother-son government" and appealed for a "good, strong mandate in Delhi to work for the people", wagging his finger in a gesture now familiar to the nation.

"Till the time you end these dynastic politics, things won't improve," Modi said to cheers in Robertsganj, another constituency voting Monday in the pivotal state of Uttar Pradesh.

The BJP has predicted "a clear majority" nationally. Indian opinion polls, which have on occasion been spectacularly wrong, also suggest the party is set for a strong victory.

Top party organiser Amit Shah said the electorate had supported the BJP "irrespective of caste (and) religion", seeking to dispel notions Modi's muscular Hindu nationalism was a stumbling block.

Modi has tried to cast off the BJP's religion-based image, pushing an agenda of good governance and economic growth in contrast to the left-leaning Congress's populist pitch.

"I believe in one India, the best India," said Modi, the chief minister of thriving Gujarat state, who is popular among business and middle-class voters frustrated by a sharp economic slowdown, high inflation and corruption scandals.

Still, 12 years ago, few would have guessed he would be in line to be premier after riots killing at least 1,000 people -- most of them Muslims -- swept Gujarat soon after he became its leader.

Modi was never charged with wrongdoing but critics allege he did too little to stop the bloodshed.

The Gandhi family made a last-ditch push with Rahul, his mother and sister, Priyanka, all on the hustings.

On Saturday, Rahul, 43, reaffirmed Congress's commitment to "empowerment of the poor", charging a BJP government would not "benefit anyone but business".

The Nehru-Gandhi dynasty has given India three premiers since independence. But bookies reckon chances of Rahul becoming premier are so minuscule they've ceased taking bets, according to local media.

Investors, confident of a BJP win, have driven shares to record highs. Few observers, though, expect the BJP to reach the magic 272 number needed for a parliamentary majority by itself.

Many anticipate fierce bargaining as regional heavyweights trade parliamentary support for political concessions.

Rahul, groomed for the party's leadership by his mother, has been dubbed the "reluctant crown prince", preferring a backroom role. Local media has judged his campaign performance uninspiring.

Priyanka, 42, regarded as more politically talented, has strongly attacked the BJP and called the election a "fight for the heart" of Hindu-majority but constitutionally secular India.

While India's 1.25-billion population is mainly Hindu, Muslims comprise 13 percent.

Even if Congress loses as expected, few observers are writing its obituary, having seen the party rebound before from devastating defeats.