Behind Mamata Banerjee’s decisive and impressive victory in the 2016 West Bengal assembly elections is the second highest vote share registered in the state by Trinamool Congress – 44.9%, against 49.1% for the Congress in 1972.

Banerjee will rule for a second term with the second largest majority of seats ever obtained by a single party or coalition – 71.77%, against 77.14% for the Congress in 1972.

Following charts and graphs contextualise this performance, confirming the comprehensive and massive character of the Trinamool’s victory and explain why there are more reasons for the Left to worry about for their future in West Bengal than the Congress.

Steady turnout

Voter participation is traditionally high in West Bengal. The average turnout has regularly been above 70% since the early 1980s and above 80% since the mid-1990s. Compared to 2011, the turnout in Bengal has decreased by 1%, at a state average of 83.4%. Sixteen seats registered a turnout above 90%.

The following map reveals that the turnout distribution is quite even – other than Kolkata and its urban surroundings. The capital’s turnout lags about 20 points behind the state average. Incidentally, Mamata Banerjee was elected in a constituency, Bhabanipur, in South Kolkata, which registered one of the lowest turnout – 67.83% – in these elections.

The contenders

There is a trend in Indian elections that more and more individuals and parties contest elections. West Bengal is no exception.

In 2016, there were a total of 56 parties, with 1,961 individuals contesting either as party or independent candidates – 68% of these candidates lost their deposit and only nine parties made it to the Vidhan Sabha.

Small parties can have a spoiler effect when they cut across the vote base of major parties. That did not happen in these elections as voters concentrated on the main contenders. The Trinamool and the Left-Congress alliance together nearly 81% of the total vote share. The BJP got 10.2% of the votes and the rest was split among 50-odd parties and independent candidates.

The average margin separating the runner-up from the third candidate is above 49,000 votes, which is another indicator that these elections were a bipolar fight.

The 2016 state elections have generally confirmed the trend that voters tend to vote more and more for major players and aren’t willing to "waste" their vote with small parties for the sake of making a statement or to support a small party on the bases of a narrow identity criteria.

Party-wise votes share

The Trinamool contested on its own this time, unlike in 2011 when it contested in alliance with the Congress.

Because it contested more seats this time, Trinamool increased its overall vote share significantly – from 38.9% to 44.9%. This is the second highest score registered in West Bengal since Independence.

But in terms of vote shares in the seats contested, the Trinamool tally of 44.9% of the votes is less than in 2011, when it bagged a majority of the votes – 50.15% – in the 226 seats it contested.

The Congress bagged an average of 40.1% of the vote share in the seats it contested, 2.5% less than in 2011, when it contested 66 seats, in an alliance with the Trinamool. Despite contesting in 34 more seats than in 2011, it only increased its overall vote share by 3%.

Therefore, any claim that the Congress has somewhat progressed in West Bengal should be taken with a pinch of salt. Its seat share marginally increased, from 13.6% to 15% (plus two seats) and its performance depended on the goodwill of its partners and their supporters.

The main loser of this election is the CPI(M), which lost a third of its voters, compared to 2011. The mainstream communist party is back to where it was in 1969. The loss is all the more humiliating that it contested in an alliance with the Congress. Survey data would be required to see whether Congress voters stayed away from communist candidates, but the partnership clearly did little to attenuate the CPI(M)’s woes.

As a result, the CPI(M) is now the third party in terms of seats, behind Congress.

The CPI(M) received 38.4% of the votes in the seats it contested – less than its partner. In all, the CPI(M)-Congress combine received 17.5 million votes, while the Trinamool received close to 25.6 million votes.

The BJP increased its vote share from 4% to 10.2%, which incidentally is not its best performance in West Bengal. The saffron party had won 11.3% of vote share in the 1991 assembly elections. Since it contested in all the seats – 292 out of 294 – its vote share in seats contested remains roughly the same at 10.4%.

In the 14 assembly segments of Kolkata, the lotus party got only 2.75 lakhs votes, that is 13% of the city’s vote share.

The Trinamool’s victory is comprehensive as it covers the entirety of the state. It’s vote share is weaker in Maldah and Murshidabad districts, where the Congress retains a good presence, and in Darjeeling and in parts of Bankura districts.

Otherwise, the party emerges victorious everywhere else. Its vote share tended to be higher in rural areas, a sign that it has – almost – completely replaced the Left as the "provider party" for the rural poor.

The CPI(M) retains an all-state presence, even if it is receding. This means that his vote share gets diluted over a large number of seats, which explains its poor conversion rate of votes into seats (26 seats for 19.75% vote share). The party has lost all its stronghold and is a second or third figure in every district.

The following map shows the spatial distribution of winners. It confirms that the Congress maintains two strongholds in Maldah and Murshidabad, that the Gorkha Janmukti Morcha has proved to be a successor to the Gorkha National Liberation Front in Darjeeling, and that the Left is a scattered force.

Margin of victory

These elections were presented as a close contest between the incumbent party and an alliance that arithmetically had the potential numbers to defeat its common opponent. A look at victory margins, however, tells a different story.

In most cases, whoever the winner was won decisively – with a premium for the Congress (13% average margin) and the Trinamool (11.9%). Both CPI(M) 6.3% and BJP 7% percent lagged behind, which shows that the winning candidates of these two parties had comparatively tougher fights than those of the other two parties. It may be a sign that the transfer of votes between Congress and CPI(M)’s did not work equally well for both sides.

Comparison with 2014 Lok Sabha elections

How did parties perform compare to the 2014 elections? To make both elections comparable, we look at the results of parties in assembly segments of parliamentary seats.

Vote shares confirm the linearity of the trends, except for the BJP who – unsurprisingly – performed better in the General elections (16.93% against 10.2% in 2016). This is a significant decrease of vote share for a party that invested a lot of energy and people for mobilisation on the ground over the past two years.

The comparison in terms of seat share (or assembly segments of parliamentary seats in the case of 2014) reveals that the Trinamool did, in fact, perform slightly better in 2014 than in 2016. Trinamool had led in 214 assembly segments while the BJP had led in 24 segments in 2014.

But looking comparatively at a party’s seat or vote share performance by itself is misleading since parties contested in different numbers of seats – and in different alliances.

For instance, the Congress has increased its vote share but it contested in more seats than in 2011. The BJP can boast about the increase in its vote share, but it contested nearly all the seats. Besides, the Congress and the Left contested in an alliance, which blurs the analysis of their stand-alone performance.

Looking at strike rates solves the issue of parties contesting in different numbers of seats. They confirm that Congress virtually disappeared in 2014 when it did not contest in a pre-electoral alliance.

Congress actually outperformed its ally, winning 44 seats with 12.3% of vote share, against 26 seats for the CPI(M) with19.7% vote share.

Party-wise seat retention

Finally, another indicator of the strength of the parties is their ability to retain their seats. Elections in India are usually marked by high volatility – anti-incumbency being one factor, among others. Parties often win and lose many seats at the same time.

In this election, the Trinamool retained 154 of its previous 184 seats, which is a rare ratio. It wrested 42 seats from Left parties and 9 from the Congress.

The Congress retained 29 of its 42 seats and won 12 new seats in constituencies previously held by Trinamool MLAs, among others.

The CPI(M) retained only 15 seats out of its 40 seats, and gained 9 of its 11 new seats from Trinamool MLAs.

The Trinamool lost only 27 seats to the Congress-Left combine, while the CPI(M) lost 31 seats to the Trinamool alone. This shows that the Trinamool and the Congress are the only two parties lying on a strong base, though of different sizes.

All these charts and indicators confirm the massive and comprehensive character of the Trinamool’s victory. They also reveal that the Congress would face oblivion if it did not tie-up with other parites. They also reveal that the Left can no longer rely on a stable geographical base from where it could organise a reconquest. Just like for the Congress at the national level, prospects in West Bengal look grim for the Left parties.

The victory of the Trinamool, just like the victory of the All India Anna Dravida Munnetra Kazhagam in Tamil Nadu or the victory of Nitish Kumar at the head of the Grand Alliance in Bihar six months ago sends the signal that parties that have a strong ground presence, and provide access to tangible resources through state policy and local patronage networks, are more likely to win elections than national or state-based parties who remain aloof from voters’ daily concerns. It clearly indicates that voters expect a return from their support. Parties that are unable to portray that role or who fail in that role are the ones to be punished by the voters regularly.

Gilles Verniers is Assistant Professor of Political Science at Ashoka University and co-Director of the Trivedi Centre for Political Data.

Asees Puri, Akashmegh Sharma, Rajkamal Singh, Venkat Prasathand Chinmay Narayan contributed to the data preparation.