As India’s opposition Congress party went down to a landslide defeat on Thursday, its leader, Rahul Gandhi, was also convincingly beaten in his own parliamentary seat – a north Indian constituency that had sent three of his family members to parliament in the past half-century.

The loss of the family bastion seat of Amethi underscored the dwindling relevance of south Asia’s most famous political dynasty in Narendra Modi’s “new India”, alongside the decline of the pluralistic vision of India that has been synonymous with the Nehru-Gandhi family for the past seven decades.

“The public is the master and the master has made its decision,” Gandhi, 48, told a press conference in Delhi, where he conceded defeat to the ruling Bharatiya Janata party (BJP) candidate, Smriti Irani. Gandhi will continue to sit in the Indian parliament in a second seat, Wayanad in Kerala state, that he won easily on Thursday.

Congress was trounced by Modi’s party in 2014 and reduced to its worst ever showing of 44 seats. It improved on that result on Thursday, but loss of Amethi and the BJP’s penetration of the country’s east, north-east and south confirmed that Gandhi’s party has been superseded as India’s only national political force.

The loss will revive questions about whether Gandhi and his family should relinquish control of Congress to fresh faces, exactly a century since his great-great-grandfather, Motilal Nehru, took the helm of the party that led India’s freedom movement.

Play Video 1:32 Narendra Modi claims landslide victory in Indian election – video report

Jawaharlal Nehru, Gandhi’s great-grandfather, fiercely opposed Hindu nationalism and sought to establish India as a secular country, a vision the modern party continues to uphold.

Under Modi, the staunchest Hindu nationalist ever to occupy the office, that tradition has been recast as a long national nightmare, blaming it even for the breakup of the subcontinent.

“It is in your character that the division of India happened,” Modi told Gandhi in parliament in February.

“The country was broken into pieces and you sowed the poison. After 70 years of independence, not a day passed when the 125 crore [1.25 billion] Indians do not get punished for your sins.”

Though dynasties continue to be common in Indian media, business and politics, Modi has successfully drawn the contrast between his biography as the son of a poor tea seller with Gandhi’s more gilded upbringing.

“The Gandhis are a comfortable family,” said BJP spokeswoman Charu Pragya, echoing a typical charge. “They like where they live, they like their life, their holidays. They are not willing to make a change. For Modi the change comes from deep within.”

Congress party stalwarts such as Sam Pitroda argue that the Gandhi family’s long history in politics should be seen as asset. “They are not kids who grew up on the street,” he told the Guardian last month. “They bring a certain pedigree.”

He recalled recently travelling to a Gulf country with Gandhi, where they met an older leader. “[The ruler] said to him: ‘When I went to India, you were three years old, and you took my headgear and put it on your head.’ He told him he was like his grandson … Now that’s an asset,” Pitroda said.

Priyanka Churvedi, a former Congress spokesperson who fell out with the party earlier this year and joined a rival, said the party needed to understand that India had changed.

“This country is extremely aspirational,” she said. “It has a majority population [younger] than 35. They are grateful to freedom fighters but they do not want to be taken back there. They want to know what is in store for them in the future.”