By Subir Bhaumik
BBC News, Guwahati
The BJP campaign will focus on migration (Photo: Subhamoy Bhattacharjee)
When Bangladesh goes to polls, the "India factor" looms large. When India votes - as it will during the general elections in April and May - the "Bangladesh factor" likewise sits heavy on the campaign in the north-east.
Right-wing Hindu nationalist parties like the Bharatiya Janata Party (BJP) are attacking the Congress - India's governing party which is also in power in a number of north-eastern states - for doing little to stop what they say is an illegal migration crisis from Bangladesh.
In Assam, the BJP's electoral ally, the Asom Gana Parishad (AGP) has joined the tirade against the Congress.
"The Congress has played the politics of the Bangladeshi vote banks for 60 years now. This time, it will not work," says AGP chief Chandra Mohan Patowary.
The Congress is quick to defend its position.
"We only protect Indian Muslims but we are against infiltration from Bangladesh," says Assam chief minister Tarun Gogoi.
Some Assamese argue their culture is being undermined
He says that Congress is a national party and it is its job to protect all kinds of linguistic and religious minorities.
"We cannot surrender our long tradition of secularism. The BJP is communal and its alliance with the AGP is opportunistic," Mr Gogoi alleges.
Congress, largely on Mr Gogoi's insistence, has stayed away from a proposed seat-sharing alliance with the minority Assam United Democratic Front (AUDF).
According to senior Congress sources, Mr Gogoi has been locked in heated exchanges with senior Congress figures such as Foreign Minister Pranab Mukherjee over this issue.
Mr Mukherjeee wants an alliance with the AUDF because the party, which won 10 seats in the 2006 Assam state polls, is seen as capable of cutting into the vote bank of Congress. He and others fear that without the support of the AUDF, Congress will be defeated in several of the 14 parliamentary seats in Assam.
"Mr Gogoi knows that an alliance with the AUDF may get the Congress a few seats in areas dominated by migrants from what is now Bangladesh but it will adversely impact on the sentiment of the ethnic Assamese," said political analyst Nani Gopal Mahanta.
"He wants to project Congress as a party of the Assamese to neutralise the campaign of the BJP and the AGP."
Muslims constitute more than 30% of Assam's population - most of whom are migrants from former East Bengal, now Bangladesh.
The 'Bangladesh factor' is expected to figure prominently in the vote
Mr Mahanta says that these migrants - new and old - are a decisive factor in nearly one-third of Assam's 126 state assembly seats.
And that's precisely why ethnic Assamese are so upset with the migrants.
It's not just the fears of continued illegal migration from Bangladesh that makes it such a big factor in polls in the north-east.
India has often alleged that north-eastern rebel groups have found shelter in Bangladesh - and the country's new Awami League government has now assured India of strong action against these groups.
The Congress, keen to play down the illegal migration issue, plays up the Bangladesh card in a different way.
"All our wanted rebels are based in Bangladesh. The new government there must throw them out and we want Delhi to pressurise Dhaka to stop sheltering them," said Mr Gogoi.
The left-leaning chief minister of the nearby state of Tripura, Manik Sarkar, has also been a target of BJP criticism for the left's alleged encouragement of illegal migration from Bangladesh. But he supports Mr Gogoi's plans to deal with the problem.
"Our states gave shelter to millions of Bangladeshis during the country's freedom struggle from Pakistan. We all made the sacrifice. The least we can expect is that Bangladesh will not shelter our trouble-makers," said Mr Sarkar.
In Meghalaya, a tribal state, "infiltration from Bangladesh" is again a big issue. A local council even announced rewards for Khasi tribal mothers if they gave birth to 15 children or more.
"That is the level of paranoia about infiltration from Bangladesh," says Meghalayan social activist and editor Patricia Mukhim.
Local parties, like the AGP in neighbouring Assam, are hyped up about "infiltration" from Bangladesh - as are the smaller tribal parties in Tripura.
"Migration from East Pakistan, now Bangladesh, has turned us into foreigners in our own homeland," says Rabindra Debbarma, general secretary of the Indigenous National Party of Tripura (INPT).
The BJP and the regional parties play up the migration issue from Bangladesh. The Congress and the left play up the issue of local insurgents getting shelter in Bangladesh.
There are a total of 24 members of parliament in India's north-east - the majority of them in Assam.
In the kind of tough competition forecast between the Congress-led UPA alliance and the BJP-led NDA alliance, every seat is going to count.
So even the big national parties are campaigning heavily in the north-east and working the right kind of alliances with local parties.
The "Bangladesh factor" is certain to loom large over the vote - it's an issue that is not easily going to go away.