On May 4, 2014, then BJP's prime ministerial candidate, Narendra Modi, distinguished Bangladeshi Hindu migrants from the Muslim ones by using the word 'refugee' for the former — “those who celebrate Durgashtami” — and “infiltrators” for the latter, "who are pouring in due to vote-bank politics". The former must be given protection and the latter driven out, he had said.
The BJP cites the data from Census 2011 to point to the increase in the state's Muslim population share, attributing it to “infiltration” from Bangladesh. It projects this share will be around 30% in the next census. It also claims the TMC government has allowed rampant infiltration since 2011 and turned infiltrators into voters. A senior BJP leader has dubbed the Mamata Banerjee government the "tees pratishat ki sarkar (a government for the benefit of the 30%)".
“All the infiltrators from Bangladesh are sitting here and harming the interests of the country. Didi has turned them into voters,” the BJP's Bengal unit President Dilip Ghosh had said in December 2020. In the absence of more recent data, changes in the demographic pattern during the Mamata Banerjee rule since 2011 can only be known after the publication of the census of 2021.
The Bengali nativist organisations, on their part, also cite numbers from Census 2011: Since native Muslims and Hindus of Bangladesh are predominantly Bengali-speaking, they question why the purported influx of migrants from Bangladesh has not increased the state's Bengali-speaking population. Both sides are using decade-old data and misinterpreting the same to create a volatile political atmosphere, said political activist Prosenjit Bose. "Those who talk about the in-migration of Hindi-speaking people do not mention the out-migration of Bengali-speaking people who have settled in other states ," he said, adding, "(This) is the key reason for Bengali-speaking population not recording any significant increase."
Bengali nativist personality Garga Chatterjee is one of the most vocal activists questioning the Hindu nationalists' Muslim infiltration theory by citing no significant increase in Bengali-speaking population. "The question is how massive is the migration of Hindi-speaking people who are eating into our resources?" he said.