Protesters in Guwahati and Shillong took to the streets after a visit by a joint parliamentary committee.
A proposed law that would give citizenship to illegal migrants from Bangladesh has stirred up the northeast against the BJP, which rules six of the seven states in the area. Illegal migration is a sensitive issue in states like Assam and some of the BJP's alliance partners are threatening to withdraw support from the coalition governments.
The Citizenship Amendment Bill 2016 seeks to allow illegal migrants from the minority communities -- Hindu, Christians and Jains -- of Bangladesh, Pakistan and Afghanistan eligible for citizenship after six years of stay in India. It was a promise by Narendra Modi ahead of the 2014 general elections in which the BJP swept to power.
But the idea has had the residents up in arms in Assam, Tripura and Meghalaya, which share a porous border with Bangladesh.
Assam has long resented the influx of Bangladeshi Muslims, citing pressure on its limited land and resources. To weed out migrants, the Assam Accord was signed in 1985, which says anyone who entered the state after 1971 would be considered an illegal resident.
Assam's BJP Chief Minister Sarbananda Sonowal is under extreme pressure from regional ally Asom Gana Parishad (AGP) which propelled it to power in the state in 2016. Ahead of the state elections in Assam, the BJP had taken a tough stand on illegal migration. Now, the AGP is threatening to quit the alliance if the centre goes forward with the bill.
The powerful All Assam Students Union, which led the Assam agitation of the 80s against illegal migrants, is spearheading the agitation against the bill in Guwahati and Shillong, which erupted over the weekend.
Yesterday, as posters with "Chief Minister Sarbananda Sonowal is missing" mushroomed across Guwahati, Mr Sonowal said, "I have no reason to continue as the Chief Minister if I can't protect the interests of the people... We will not take any decision that goes against the people of Assam'.
Meghalaya Chief Minister Conrad Sangma told NDTV that his National People's Party, which leads the NDA government in Meghalaya, is opposed to the bill. "The entire cabinet feels that the bill is undemocratic and against the interests of the country," he added.
Barring Mizoram, the other six states in the northeast - Assam, Nagaland, Meghalaya, Arunachal Pradesh, Manipur and Sikkim -- are now with the BJP, which would make it especially tough for the party to garner support as the general elections scheduled next year draws close.