Activists take part in a torch light rally procession to protest against the bill in Guwahati. (PTI)

The Bharatiya Janta Party may increasingly find it difficult to push through the Citizenship (Amendment) Bill 2016 fearing the risk of losing its allies in the Northeast, party sources have told NDTV. The region has been witnessing wide scale protests ever since the controversial Bill was introduced in Parliament earlier this month and passed by the Lok Sabha.

In BJP-ruled Assam, protests have been taking place for the fifth week with the opposition Congress also taking out rallies across the state vehemently opposing the Bill.

The agitation on the issue in Assam - a region where it has done phenomenally well since 2014 - has put the party on the back foot. Chief Minister Sarbananda Sonowal recently told the assembly that the provisions of the Assam Accord will not be violated by the Citizenship bill.

"The Citizenship Bill is for entire nation, not only Assam... Then why unnecessary fear is being created among people? From where has this figure of 1.9 crore Hindu Bangladeshis coming to Assam emerged?," he told the Assembly.

"We should not confuse people by saying that Assamese identity and culture will be finished. The opposition should behave responsibly," he added.

On Friday, Mr Sonowal claimed "unnecessary social disturbance" was being created over the bill ahead of the Lok Sabha polls.

In a grand show of strength, 10 political parties based in the northeastern region, including BJP allies and the JD(U) came together on Tuesday to oppose the citizenship amendment bill and ensure that it is not passed in the Rajya Sabha. Mizoram Chief Minister Zoramthanga, who was also present at the meeting, said that the bill which was "dangerous and harmful for the people of the northeast."

A BJP leader was recently beaten up by those protesting against the citizenship amendment bill in Assam's Tinsukia district.

In his address to parliament, the President also spoke on the bill. "Citizenship Amendment Bill will make it easier to provide Indian citizenship to those who had to take refuge in India after facing oppression somewhere else. They were not at fault; they were victims of situations like that" President Ram Nath Kovind told the parliament.

But the President's address has failed to calm nerves.

The BJP's popularity has also taken a hit in Tripura, where it came to power with the support of its tribal ally nearly a year back, creating electoral history. Now, the tribals in the state are cutting across political lines to protest against the controversial bill.

"We have all gathered non politically and send a message to (Prime Minister) Narendra Modi that first they should think of people of northeast, then migrant. It's not about politics but about our existence" said Pradyot Manikya Debburman, Tripura 's Royal Scion and Working President of Congress in Tripura.

Two BJP legislators in Meghalaya have threatened to quit the party if the bill is tabled in the Rajya Sabha. A delegation from the state headed by Meghalaya chief minister Conrad Sangma is already in New Delhi meeting key NDA allies urging them not to vote in favour of the bill in Rajya Sabha.

For the BJP, the 25 Lok Sabha seat in the northeast is very important. In 2014, it won eight seats on it own, while its allies won four. Rest of the 13 seats were won by non-NDA parties.

Ever since the BJP came to power at the Centre in 2014, its average vote share in the northeast has grown 23.1 percentage points from 3.9% to 27%. Out of the 38.18 percent votes that the NDA got in Northeast in 2014, regional parties had got over 24 percent f those vote.

In the 2014 general election BJP and its regional partners together got 38.18 percent of vote share, non NDA parties got 61.82 in the 25 seats in Northeast.

Since 2014 BJP's vote share has increased to 27 percent in the region, while its allies vote share is 24.61 per cent.

The Citizenship Amendment Bill has been passed in the Lok Sabha, but it has not been listed by the government in the Rajya Sabha where it is short on numbers. BJP's ally Janata Dal-United (JD-U) has already announced its opposition to the bill.