The left in India operates on the assumption that caste=class, thus it aims to be the voice of the lower castes and minorities (often there is an overlap). Typically this USP worked in the Left’s favor during its 34 year (mis)rule in West Bengal. The minorities wanted an assurance that they will not be victimized by riots (1984/1992/2002) and the Left (mostly) kept its end of the bargain.
A few things changed with time. The left aligned with big business and the police targeted (mainly) minorities in Nandigram. As a reaction the influential bhadralok (elite) opinion makers went against the Left. Due to the shift in public opinion Mamata Banerjee was able to capture the minority vote and get a huge majority in her favor.
Once in power Mamata wanted to ensure a way to keep the minority vote in her pocket. She announced special grants for madrassa education as well as monthly income schemes for imams of “recognized” mosques (10,000 in all).
It was left to “secular” muslims to spell out exactly how this plan is a disaster. It polarizes hindus vs muslims (where are the grants for sanskrit studies?), and the “recognized” imams will be expected to ask their followers to vote for MB.
The announcement of the leader of the ruling party will deprive the namazis of their right to decide who will be the imam at a particular time. To get the allowance the imam’s name has to be registered in the government records. Those who have seen the activities of the leaders of the ruling party will have no doubt that they will not select the eligible person, but the one who supports them. This supporter can be the most detestable person in the eyes of the namazis, and worse, once his name is registered, whether he remains an imam or not will not depend on the namazis but the leaders of the ruling party through the government employees. Even if he commits a thousand sins and loses the right to be imam, it will not be possible to remove him without the wish of the ruling party leaders.
Evidence of the polarization came soon enough in the Jangipur (Murshidabad district) parliamentary elections contested by the son of Pranab Mukherjee (who quit to become President of India). Mamata graciously did not contest the seat. But the BJP and various muslim parties did contest. The left lost by a miniscule (-)2,500 votes (Pranab’s margin in the previous election was +300K).
The CPM (Communist Party) fear has its root in the increased vote share of the BJP and Islamic parties like the Welfare Party of India (WPI) and Social Democratic Party of India (SDPI). WPI is the political wing of the Jamaat-e-Islami Hind while SDPI includes former members of the Popular Front of India that is a confederation of Muslim organizations.
About 10% votes went to the BJP, WPI got 4% and SDPI about 3% of the votes. BJP’s vote share in Bengal almost always hovered around 6%. In the 2011 assembly polls, that uprooted the 34-year-old Left Front government, BJP got about 4.4% votes.
Due to infiltration from Bangladesh, Murshidabad has now become a minority-majority district. This and the impact of govt policies have ensured that the Hindu vote may decide the election. Eventually the islamist parties would gain strength and become part of the Mamata coalition (as has happened in Kerala). The Hindu vote will then migrate (preferentially) to the Left (same as Kerala). At that point the left will become the natural home of (evil, reactionary) upper caste Hindus. Marx will no doubt be strongly displeased.