The BJP is likely to get 56 of the 80 parliamentary seats in strategically vital Uttar Pradesh, according to NDTV's exit poll. The outsize tally will play a key role in helping the BJP to cross the 272-mark to form the government with its existing allies. (
Full Coverage: NDTV Exit Polls)
That is massive gain over 2009 when the party won just 10 seats.
Mulayam Singh Yadav's party is a very distant runner up with 12 seats, that is 10 less than last time.
Mayawati's Bahujan Samaj (BSP) Party gets eight seats, a drop of 12 from 2009.
The Congress plummets to four seats. In 2009, it got 22 seats.
Narendra Modi, the BJP's prime ministerial candidate, is contesting his first parliamentary election from Varanasi in UP. His main challenger is Arvind Kejriwal, head of the Aam Aadmi Party.
Mr Modi asked his top aide, Amit Shah, formerly Minister of State for Home in Gujarat, to run the BJP campaign in Uttar Pradesh. Mr Modi campaigned extensively across the state including in Amethi, the constituency of Congress Vice President Rahul Gandhi.
The Congress, fronted by Mr Gandhi, is expected to be saddled with one of its worst performances ever.