The BJP's Eatala Rajender coasted to victory in the bypoll for Telangana's Huzurabad Assembly constituency, beating the ruling TRS' Gellu Srinivas Yadav by nearly 24,000 votes.
Mr Rajender polled around 1.07 lakh votes to Mr Yadav's 82,712. The Congress' Balmoor Venkat Narsing Rao finished a distant third with just 3,012 votes.
The Huzurabad battle was keenly observed because Mr Rajender - who has won the seat in every election since 2009 - quit the Telangana Rashtra Samiti in June over corruption allegations.
Seen as one of those who, with Chief Minister K Chandrashekar Rao, led the movement for a separate Telangana, Mr Rajender has denied all charges.
Nevertheless, Mr Rajender (then the Health Minister) resigned as Huzurabad MLA and quit the TRS.
He joined the BJP days later in Delhi, in the presence of party chief JP Nadda.
The bypoll, therefore, became a matter of prestige for both parties.
Full Assembly elections are still two years away, but the outcome of this bypoll could influence political developments in the state.
The TRS had hoped to win because victory for Mr Rajender will give other disgruntled leaders in its ranks hope that they too can challenge KCR's leadership and might win seats if they jump to the BJP.
Interestingly, the party chose student leader Gellu Srinivas Yadav as its candidate. Concerns that defeat for a senior leader would be embarrassing likely played a role in that calculation.
Telangana Finance Minister Harish Rao, who is also the Chief Minister's nephew, was made poll-in-charge for the ruling party, and neither KCR nor his son, KT Rama Rao, campaigned there.
For the BJP it was key to win Huzurabad after winning the Dubbak bypoll and performing well in Hyderabad's municipal elections.
This win, coming as it does amid reverses for the party in Himachal Pradesh, will boost the BJP's hopes of emerging as a challenger to the TRS in the 2023 election.
The Congress had demanded a postponement of the election, which was held on Saturday.
"TRS and BJP are buying votes for Rs 6,000 and Rs 10,000. The Huzurabad by-election has become the costliest in the country... this is being debated on TV channels in Telangana. There is no meaning of democracy left if votes are to be bought," spokesperson Randeep Surjewala said.
Meanwhile, in neighbouring Andhra Pradesh, the ruling YSR Congress' Dasari Sudha claimed an emphatic win for the Badvel (reserved for marginalised communities) seat, securing over 1.12 lakh votes, which is more than double the party's winning margin in 2019.
The BJP's Panathala Suresh was a (very) distant second with less than 22,000 votes, and the Congress' Kamalamma PM was third with around 6,200 votes.
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