Tamil Nadu · Declared Assembly By-Election Returns
TVK won both seats. In each, the sitting AIADMK MLA resigned and re-contested on a TVK ticket.
Hover or tap highlighted seats for declared details
Winning margin equals 10.82% of all ballots cast. See every candidate ↓
Winning margin equals 5.25% of all ballots cast. See every candidate ↓
Every metric compares the October 2026 by-election with the May 2026 general election baseline. Deltas indicate changes in percentage points (pp).
In both seats, the May AIADMK winner resigned and re-contested on a TVK ticket. Comparing the individual candidates' own vote shares reveals how personal support held up versus the party ticket.
AIADMK votes fell by 21,834, exceeding the 12,959 ballot decline in total turnout.
AIADMK votes fell by 35,820, exceeding the 19,412 ballot decline in total turnout.
Step-by-step arithmetic from May leader to October winner
Arithmetic: 34.95% (May leader) -3.63 pp (TVK deficit) +8.64 pp (TVK gain) = 39.96% (Oct winner)
Step-by-step arithmetic from May leader to October winner
Arithmetic: 40.56% (May leader) -17.33 pp (TVK deficit) +13.79 pp (TVK gain) = 37.02% (Oct winner)
Baseline: May 2026 Tamil Nadu General Assembly Election certified returns.
Party gain: Difference in party vote share in percentage points (Oct share − May share). Note that TVK fielded different candidates in May, so party gains capture both ticket switching and party popularity.
Candidate continuity: Directly compares the same candidate's votes and share under AIADMK in May 2026 versus TVK in October 2026.
Lead bridge arithmetic: May leader share + TVK May deficit + TVK vote-share gain = October winner share.
| Party | Madurantakamமதுராந்தகம் | Dharapuramதாராபுரம் | Combined Total |
|---|---|---|---|
| TVK | 39.96%74,048 votes | 37.02%66,841 votes | 38.51%1,40,889 votes |
| DMK | 29.15%54,008 votes | 31.78%57,370 votes | 30.45%1,11,378 votes |
| AIADMK | 25.61%47,450 votes | 25.08%45,280 votes | 25.35%92,730 votes |
| NTK | 1.46%2,709 votes | 2.92%5,268 votes | 2.18%7,977 votes |
| Other candidates | 3.47%6,425 votes | 2.82%5,096 votes | 3.15%11,521 votes |
| NOTA | 0.35%652 votes | 0.38%677 votes | 0.36%1,329 votes |
| Total Polled | 1,85,292100% | 1,80,532100% | 3,65,824100% |
Dharapuram was the closer contest: 9,471 votes (5.25%), compared with 20,040 votes (10.82%) in Madurantakam. Both finished under the historical 14.2% Tamil Nadu by-election average.
Heat-table shading: Cell background opacity scales from 0% to 50% vote share.
Combined total: Sum of candidate votes across both seats divided by total ballots cast in both seats (3,65,824).
Winning margin benchmark: 14.2% represents the historical average victory margin across Tamil Nadu assembly by-elections (2006–2024, n = 16 standalone contests).
864 postal votes cast (0.47% of total polled). Winner received 137 postal votes (0.19% of winner total).
3,534 postal votes cast (1.96% of total polled). Winner received 255 postal votes (0.38% of winner total).
Effective Number of Parties (ENP): Computed via the Laakso-Taagepera formula: ENP = 1 / Σ(s_i²), where s_i is each candidate's vote share. A score of ~3.2 reflects a true three-cornered contest.
Security deposit threshold: Under ECI rules, candidates polling less than 1/6th (16.67%) of total valid votes forfeit their deposit.
All other candidates combined vs margin: Sum of all votes cast for candidates outside the top two compared directly against the victory margin.
Historically in Tamil Nadu (2006–2024, n = 16 standalone by-elections), the state ruling party won 14 of 16 contests (87.5%), with an average victory margin of 14.2%. In October 2026, ruling DMK finished second in both seats, and both flipped to new entrant TVK with below-average margins.
Sample size: N = 16 standalone Tamil Nadu assembly by-elections held between 2006 and 2024. Excludes general elections and the May 2019 22-seat concurrent assembly by-polls.
Ruling alliance win rate: The state ruling alliance retained or won 14 out of 16 contests (87.5%). The only prior opposition/independent flips in this period were Alandur (2014) and Radhakrishnan Nagar (2017).
Turnout contraction: Assembly by-polls typically experience a 5–10% decline in ballots cast compared to the immediately preceding general election. The 2026 drop of 8.1% aligns with this pattern.
| Rank | Candidate | Party | Votes | Vote share | Behind winner |
|---|---|---|---|---|---|
| 1 | K. Maragatham KumaravelElected | TVK | 74,048 | 39.96% | Winner |
| 2 | I. Paranthamen | DMK | 54,008 | 29.15% | 20,040 votes |
| 3 | S. Kanitha Sampath | AIADMK | 47,450 | 25.61% | 26,598 votes |
| 4 | G. Janakiraman | NTK | 2,709 | 1.46% | 71,339 votes |
| 5 | P. Suganthi | CPI(M) | 1,986 | 1.07% | 72,062 votes |
| Total, including NOTA | 1,85,292 | 100% | |||
| Rank | Candidate | Party | Votes | Vote share | Behind winner |
|---|---|---|---|---|---|
| 1 | P. SathyabamaElected | TVK | 66,841 | 37.02% | Winner |
| 2 | S. Suganya | DMK | 57,370 | 31.78% | 9,471 votes |
| 3 | K. Banumathi | AIADMK | 45,280 | 25.08% | 21,561 votes |
| 4 | M. Karthika | NTK | 5,268 | 2.92% | 61,573 votes |
| 5 | P. Lakshmanan | CPI | 1,157 | 0.64% | 65,684 votes |
| Total, including NOTA | 1,80,532 | 100% | |||
TVK won both constituencies (Madurantakam and Dharapuram), flipping both seats previously held by AIADMK. TVK candidate K. Maragatham Kumaravel won Madurantakam with 74,048 votes (39.96%), and P. Sathyabama won Dharapuram with 66,841 votes (37.02%). In each seat, the sitting AIADMK MLA resigned and re-contested on a TVK ticket.
In Madurantakam, TVK won by 20,040 votes (10.82% margin) over DMK's I. Paranthamen (54,008 votes). In Dharapuram, TVK won by 9,471 votes (5.25% margin) over DMK's S. Suganya (57,370 votes). Both margins finished under the historical 14.2% Tamil Nadu by-election average.
In Madurantakam, K. Maragatham Kumaravel increased her personal vote share from 34.95% (as AIADMK MLA in May) to 39.96% (as TVK MLA in October), a personal gain of +5.01 pp (+4,764 votes). In Dharapuram, P. Sathyabama polled 40.56% in May under AIADMK and 37.02% in October under TVK, a personal decline of −3.54 pp (−14,259 votes), showing that TVK’s headline gain (+13.79 pp) primarily reflected the ticket change.
Across both seats, 32,371 fewer ballots were cast (−8.1%), dropping from 3,98,195 votes in May to 3,65,824 votes in October. AIADMK votes fell by 21,834 in Madurantakam and 35,820 in Dharapuram, declines that exceeded the overall drop in voter participation.
Historically, the ruling alliance wins 87.5% of Tamil Nadu by-elections (14 of 16 contests between 2006 and 2024). In October 2026, ruling DMK was defeated in both contests, marking a rare simultaneous double-flip to an opposition party.
5 assembly seats remain vacant across Tamil Nadu (Perundurai, Karur, Tiruchirappalli East, Viralimalai, and Ambasamudram). Track notification timelines and judicial stays.
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