Prime Minister Narendra Modi's party is well ahead of rivals in an election in the country's most populous state, Uttar Pradesh, but may fall short of an absolute majority, four major exit polls showed on Thursday.
Victory for Modi's Bharatiya Janata Party (BJP) in Uttar Pradesh, which is home to 220 million people, would boost his chances of winning the 2019 general election and underscore his popularity after he made himself the face of the party's campaign.
The prime minister would also see success as vindication of his sudden decision in November to abolish high-denomination banknotes to rein in corruption.
The move was seen as politically risky, because most transactions in India are carried out in cash and millions of Indians were forced to join long queues outside banks to deposit their old bills or get hold of new ones.
Indian elections are notoriously hard to call, and polls taken before and after voting are often wrong. Pollsters were left red-faced in 2015 after mistakenly predicting a BJP win in the state of Bihar.
Results in Uttar Pradesh, as well as four other state ballots, will be announced on Saturday.
MAGIC NUMBER
The BJP would need to win 202 seats to secure a majority in the 403-seat assembly in Uttar Pradesh, where voting ended on Wednesday almost a month after the first of seven voting phases kicked off.
If no groups wins a majority, parties on Saturday will start trying to form a governing coalition.
The BJP would win 179 seats, according to an average of four exit polls compiled by news channel NDTV, ahead of an alliance between the ruling Samajwadi Party and the Congress party that is seen picking up 136 seats.
Modi threw himself into the battle for Uttar Pradesh, where his BJP won by a landslide in the 2014 general election, to shore up its core Hindu voter base after his party's campaign got off to a weak start.
"Exit polls are not able to assess the real voting patterns. The truth will be out on Saturday and we are confident of our victory," said Samajwadi Party national spokesman Ghanshyam Tiwari.
Most people in Uttar Pradesh vote along social and religious lines, forcing parties to appeal to more than one group to clinch a vote share of more than 30 percent that can deliver a landslide win under India's first-past-the-post system.
Thursday's exit polls also forecast a neck-and-neck race between Congress and the anti-corruption Aam Aadmi Party in Punjab, where the ruling coalition, of which the BJP is a member, faces a drubbing.
Polls predicted that Modi's party would retain power in the small state of Goa and take the northern state of Uttarakhand from Congress, and put the BJP narrowly ahead in Manipur, a small region bordering Myanmar.
The BJP last ruled Uttar Pradesh in 2002.
 "Exit Polls 2017: Advantage BJP in UP but Modi may fall short of majority")
