As vote-counting trends on Thursday showed Prime Minister Narendra Modi's ruling party winning 285 seats against just 53 for Congress, current and former party officials blamed a lacklustre campaign and a failure to overhaul its top team.

"If they want to change anything, change the leadership," said a Congress official in the western state of Rajasthan, referring to the old guard around Gandhi. "You need to give young people a chance."

He was among five current and three former party officials who told Reuters that Gandhi's inability to jettison older leaders responsible for a major debacle in the 2014, general election and push forward newer, younger faces was a mistake.

All eight sources sought anonymity.

Gandhi's office did not respond to a request from Reuters for an interview.

Still, the 48-year-old Gandhi remains powerful within a party that has ruled India for most of its history since independence from Britain in 1947, and is unlikely to face a leadership challenge immediately.

But Congress's continued slide has raised questions both about its future and the role of his family.

Younger Indians find it difficult to accept that Gandhi was appointed Congress president only because of his lineage as the son, grandson, and great-grandson of prime ministers, said prominent historian and columnist Ramachandra Guha.

"The Congress should dump the Dynasty," he said on Twitter.

In May 2014, after Congress slumped to its worst performance in a general election, with 44 seats, Gandhi told reporters, "There's a lot for us to think about, and, as vice president of the party, I hold myself responsible."

Five years on, his party has suffered a further drubbing at the hands of Modi's Hindu nationalist Bharatiya Janata Party and he was himself trailing in the family borough of Amethi in northern Uttar Pradesh, though he was leading in a second constituency from which he is contesting, in southern India.

Congress also proved unable to effectively parry Modi's campaign emphasis on national security, after aerial clashes and heightened tension with arch rival Pakistan following a suicide attack in disputed Kashmir that killed 40 Indian policemen.

At the end of last year, Congress's hopes of upsetting Modi had increased, after it won three heartland states in elections, largely driven by voter concerns about weak farm incomes and a lack of jobs.

But Congress fumbled communications on key policies, with a publicity campaign this year that escaped the notice even of some of its own workers, and failed to forge pre-election alliances in key states, said the party officials who spoke to Reuters.

The campaign was substantially delayed because of disagreements between 66-year-old Anand Sharma and other senior leaders, two party officials said.

Sharma denied the accusation, saying that putting together the campaign was a complex process. "There was no delay whatsoever in the launch of Congress campaign," he added.

The campaign was launched on April 7, just four days before the first round of voting began in a general election spread over seven phases across 39 days.

In Rajasthan, which Congress won last year, its choice of 68-year-old Ashok Gehlot as chief minister, instead of 41-year-old Sachin Pilot, backfired, losing it the support of a key caste grouping, the official said, leaving the BJP likely to sweep all 25 seats.

"COLLEGE OF SYCOPHANTS"

Gandhi was encircled by a "college of sycophants", said a former Congress official who joined a rival bloc this year.

"It doesn't matter if you have talent or merit," the former official said, adding, "What matters is you have the right family name or the right mentor."

In contrast to Modi, a tea vendor's son who rose through party ranks, Gandhi's lineage is a weakness the prime minister has repeatedly exploited.

In Uttar Pradesh, which elects the bulk of India's lawmakers, Congress this year drafted in Gandhi's charismatic sister, Priyanka Gandhi Vadra, to burnish its fortunes. But that made little difference to results.