The actual votes will be counted on Tuesday, and exit polls have been wrong in the past, partly because of the sheer scale of Indian elections involving millions of votes.
Still, nearly all the polls showed that the Congress - led by Rahul Gandhi, the scion of the Nehru-Gandhi family - will win a clear majority in western Rajasthan state and scrape through in eastern Chhattisgarh, according a survey of surveys pulled together by NDTV.
In Madhya Pradesh, the same polls suggested the BJP and the Congress were locked in a fight down to the wire.
The three states are part of the northern Hindi belt, a bastion of the ruling Hindu nationalists.
"The BJP is struggling everywhere, for all its bravado," said Juhi Singh, a spokesman of the regional Samajwadi Party.
Modi, who came to power with a sweeping majority in 2014, has been praised for improving governance and cutting some red tape, but has been criticised for failing to create enough jobs for the thousands of young people entering the jobs market every month.
He has also faced criticism for allowing hardliners in his party to undermine India's secular foundations.
"The result would be consistent with what most polls are showing: that we are heading for hung parliament," said Jan Dehn, head of research at emerging markets fund manager Ashmore.
"The market may discount the results a little bit given these are state elections and there are often protest votes."
But a divided parliament would make it difficult for the incoming government to carry out reforms in the banking sector and other areas, he said. (Reporting by Sanjeev Miglani and Alasdair Pal Editing by Andrew Heavens)
(This story has not been edited by Devdiscourse staff and is auto-generated from a syndicated feed.)