As the campaigns roll on in Gujarat, news reports and opinion polls suggest that the Assembly elections promise a close two-way contest between the BJP and the Congress.
That in itself is an achievement of sorts for the Congress. If the Assembly segment trends in the 2014 Lok Sabha elections are anything to go by, the party has quite a mountain to climb against the BJP, which has been ruling the State on its own for 19 years.
In 2014, the BJP, which has been in power in Gujarat since 1998, achieved a peak in support, winning all 26 constituencies.
The BJP led in 165 Assembly segments (59.05% vote share), while the Congress led in only 17 (32.86%).
What is the quantitative shift — what psephologists term the “vote swing” — required for the Congress to overcome the BJP? If the Congress had to win at least 92 of the 182 seats (to win a majority), it required a uniform swing of exactly 11.2 percentage points from the BJP in the entire State, considering the 2014 data for each Assembly segment and assuming that this is indeed a bipolar contest.

The results of the Lok Sabha election 2014 are taken as the base instead of those of the 2012 Assembly polls, because the former marked a watershed in Indian politics, shifting it decisively and propelling the BJP to its central pole.
Taking into account the fact that the State has internal dynamics with political support varying across regions, it is more prudent to consider a regional breakdown of the swings required to win a majority.
In Saurashtra and Kutch, the Congress required a swing of 12 percentage points to win 27 of the 54 seats; in north Gujarat, it required a swing of 10.5 percentage points to win at least 27 of the 53 seats; in central Gujarat, it required a swing of 10 percentage points to win 20 of the 40 seats and in south Gujarat, it needed a whopping 14.5 percentage point swing to win at least 18 of the 35 seats.
Thus, the Congress needs nothing short of an anti-incumbency wave to defeat the BJP three years since the peak performance of the latter in 2014.
Such a turnaround is not unprecedented post-2014 — the BJP’s vote share dropped 14 percentage points in the Delhi Assembly elections in a triangular contest benefiting the Aam Aadmi Party.
The BJP has a formidable organisation; Prime Minister Narendra Modi, who served as Chief Minister for 13-and-a-half years, is still popular — subjective conditions that continue to favour the BJP.
Yet, there are objective reasons for the wind behind the Congress’s sails.
The lingering effects of demonetisation and misgivings with GST implementation has hurt the standing of the Union government.
Besides these, recent socio-political movements — the Patidar agitations and the Dalit land and self-respect agitations, among several — have also contributed to a certain momentum against the State government.
(With data and inputs from Vignesh Radhakrishnan)