AIADMK workers started celebrating as early reports indicated that Tamil Nadu Chief Minister J Jayalalithaa was leading by 20,000 votes in the counting of the RK Nagar by-polls.
The counting is still in progress.
The RK Nagar seat fell vacant following the resignation of P. Vetrivel.
The DMK, PMK and VCK have boycotted the by-election for various reasons.
A total of 28 candidates are in the fray in this assembly segment.
