Number Theory: Can AAP win Delhi for the third time?

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Elections to the Delhi assembly will be held on February 5 and the counting of votes will take place on February 8. The Aam Aadmi Party (AAP) emerged as the second largest party in the first assembly election it contested in 2013 and formed a government with the outside support of the Congress, though that government did not last long. It won an overwhelming 67 and 62 assembly constituencies (ACs) in the 2015 and 2020 elections. Can it win Delhi

AAP national convenor Arvind Kejriwal (centre) with Delhi CM Atishi (to his right) and party leaders Raghav Chadha, Sanjay Singh and others. (PTI)

Can AAP win Delhi for the third time?

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  Did the AAP peak in Delhi in the 2015 elections?

  A reading of vote shares and seat shares in assembly elections suggests so. From a vote share and seat share of 29.5% and 40% in 2013, AAP won a massive 54.34% of the vote share in the 2015 elections leading to a seat share of 95.7%. In 2020 both the vote share and seat share of AAP came down marginally compared to 2015. To be sure, a 50% plus vote share, which is what AAP still had in 2020, is an extremely formidable number in a first-past-the-post (FPTP) electoral contest.
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  How skewed is AAP’s support base in Delhi?

  This is another interesting question. A headline vote share number of 50% does not necessarily mean that a party has similar levels of support in every AC. If this were to be the case it would win all seats in the assembly. The number of ACs where AAP had a vote share of 50% or more was one in 2013, increased to 54 in 2015 and fell to 48 in the 2020 elections. A slightly more technical measure of the skew in AAP’s vote share can be done by a quintile-wise (bottom to top 20%) comparison of its vote shares across ACs in the 2013, 2015 and 2020 assembly elections. Data shows that AAP’s vote share spread was both formidable and consistent across four-fifths of ACs in both 2015 and 2020. To be sure, it won ACs even in the bottom quintile of vote shares.
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  How much of a vote swing can make the AAP lose Delhi?

  There are two ways to look at this question. In the 2020 assembly elections, AAP and BJP had a 92.1% vote share distributed between themselves, as the Congress vote share fell to just 4.26%. If the Congress were to remain where it was in 2020, then it would take just a six-percentage point swing – voters leaving AAP for BJP – for the AAP to fall below the majority mark in the Delhi assembly.
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  AAP also stands to lose if its voters were to shift to non-BJP parties

  AAP’s debut in 2013 assembly elections produced a hung assembly. However, the 2015 and 2020 elections actually led to an unprecedented level of bipolarity in Delhi’s electoral contest. One way to look at this is the sharp fall in number of ACs with spoilers in the 2015 and 2020 elections. We define a spoiler as a party/candidate with a third position in an AC having a vote share greater than the winning margin percentage of the winner. In the 2013 elections, there were spoilers in 63 ACs. This reduced drastically in the 2015 and 2020 elections to 12 and 9 ACs respectively. Not only has the AAP gained from the polarisation of contest in Delhi – its rise is basically a result of a decimation of the Congress even as the BJP has held its core vote – it also won a majority of the ACs where there were spoilers in 2015 and 2020. If the Congress or other non-BJP parties were to increase their vote share in these elections, it would definitely hurt the AAP. Will a potential anti-incumbency after having been in government for 10 years lead to a multi-directional erosion of AAP’s formidable support base in Delhi? We will know on February 8.