ended up as the single largest outfit in the 403-member assembly, thanks mainly to the 51-year-old Mayawati who came from nowhere to take everyone by storm.
In 1984, when BSP was born, few gave the party that aggressively championed the Dalit cause a great future. Mayawati had just resigned as a teacher from a state owned school in Delhi. Nobody knew her.
Daughter of a telecommunication employee, her ambition had been to become a district magistrate. She passed out from the universities of Delhi and Meerut, studying law and then took a course in teaching.
BSP's founder leader Kanshi Ram was the one who spotted Mayawati and decided to groom her. It was a turning point for the BSP.
In no time, Mayawati proved more than a good pupil. She was the perfect oxygen for a grouping that was growing in a state where the Hindu upper castes had held sway for centuries and where Dalits were traditionally held in contempt.
Mayawati was a powerful speaker in Hindi. She combined her boundless energy, commitment to Dalit society and loyalty to Kanshi Ram to unleash a campaign that numbed the upper castes.
It helped that she was a Jatav, the most upwardly mobile sect among Dalits.
If Kanshi Ram was soft spoken, Mayawati could scream. And she would raise her lungpower to thunder before tens of thousands that she was a Dalit and proud to be one -- and to hell with the upper castes.
Mesmerized, millions of Dalits and even Muslims in Uttar Pradesh deserted the Congress, a party they had supported for decades, and drifted to Kanshi Ram and Mayawati.
Once she became chief minister of Uttar Pradesh in 1995, the first Dalit to run a state in India, she refused to dilute her pro-Dalit stance, immensely pleasing her humble supporters who had got used to seeing Dalit politicians losing steam once in office.
The 1995 stint lasted just four months, and a second tenure at the head of the Uttar Pradesh government in 1997 ended in six months. By then, the "Bahenji", or sister as she was known, had become an icon of Dalit politics.
Blessed by Kanshi Ram, Mayawati returned to rule the sprawling state of Uttar Pradesh - population 166 million, equivalent to two Germanys - in 2002. Now she ruled for about a year.
By then, the once simple woman who was seen in oily plaits and ponytails had switched over to bobbed hair. She dressed well. Somewhere along the road she even eclipsed Kanshi Ram, whose death left her the supreme master of BSP.
She bought a bungalow near New Delhi's diplomatic enclave. But she still avoided the media and the upper crust - unless she needed them.
Her 2003 birthday in Lucknow was a gala affair, involving a 51 kg cake, 100,000 ladoos, 60 quintals of marigold flowers and 5,000 bouquets.
Corruption charges followed. But Mayawati only grew in popularity, deftly dropping her anti-upper caste vitriol in a bid to embrace everyone to build a large social umbrella like the Congress had for decades.
It was a masterstroke. Mayawati made it clear that she would shake hands with the support base of her opponents over the heads. Instead of begging for support from parties of the upper castes, she would herself go to the upper castes.
It is this that has made Mayawati the most powerful politician in the seven-phase Uttar Pradesh ballot that ended on May 8.
"Mayawati has pursued power with a single minded devotion," political analyst GVL Narasimha Rao told. "She does what she says and unlike other parties does not dilute her politics once in power."
Like almost everyone else, Rao predicts a long innings for Mayawati.
"She is going to be around for a very long time, indeed as long as she is alive," he said. "Today, minus Mayawati, the BSP is a big zero. She is going to be a major player in Indian politics for a long, long time."