The opposition BJP on Thursday retained the Bhorang assembly seat, its stronghold, in the by-poll voting for which was held on Sunday, an election official said.In a straight contest, the Bharatiya Janata Party's Anil Dhiman, a physician by profession, defeated Promila Devi of the Congress by a margin of 8,290 votes.Dhiman polled 24,434 votes against 16,144 votes of Promila Devi, an Election Commission official told IANS.The by-poll was necessitated following the death of two-time former Cabinet Minister I.D. Dhiman, who had won six consecutive elections from this constituency.Anil Dhiman, who was leading in all the 12 rounds of vote count, is the son of the late I.D. Dhiman.The election was held on April 9 and saw over 63 per cent voting.Leader of Opposition and two-time BJP Chief Minister Prem Kumar Dhumal told reporters that this victory was a clear indication that the party was going to form the next government in the state.The assembly elections are due in December.