WHY, and when, does a politician defect? The simplistic, but not all that simple, answer is money. We have good reason, of course, to be cynical about the morality of politicians. But if money alone was sufficient to buy the loyalty of legislators, there would be serial instability. Too many politicians, to paraphrase Oscar Wilde, can resist everything but temptation. Defection remains an occasional game because money is, at best, a one-time payoff.

When three MLAs from the Left and three from Congress switched sides to send a fourth Trinamool candidate to the Rajya Sabha last week, they were signalling something more significant than the variable role of money in public life. They delivered a political message: the Left Front was dying, and Congress was comatose in Bengal.

The CPI(M) is still alive, although not well, but it is time to draft notes on an obituary for the Left Front, a coalition of principal and junior partners who built up one of the most extraordinary political machines in modern history. The CPI(M) still has the strength to wave the red flag, but small parties who added incremental, but critical, percentages to its vote share are being squeezed out of political margins.

Two of the MLAs who abandoned the left, Dasrath Tirkey and Ananta Adhikari, were from RSP, a party which once promised both revolution and socialism. The third MLA, Sunil Mondal, is from Forward Bloc, another outfit that no longer knows why it exists. All are Scheduled Caste and Tribe leaders. Once the underprivileged walk away from a Marxist fortress, you know that the ramparts have become vacant.

The Congress is in equally grave trouble. It lost support in Malda, a seat which remained loyal even through the decades of left ascendancy, thanks principally to the local influence of the Ghani Khan Choudhary family. The veteran Ghani Khan has passed away. His brother Abu Naser, an MLA, did not vote on party lines. His colleague Emani Biswas, from neighbouring Murshidabad, refused the compromise of half-measures and gave his vote to Mamata Banerjee. This rebellion could reduce Congress to just one seat in Bengal after the coming general elections.

The great churn in Bengal makes sense if you know how to decipher the emerging political mathematics. Mamata Banerjee is the new establishment, and will remain there for the next few years, but the Marxists are no longer in command of opposition space. This is not merely because their organisation has imploded. A party built on a cadre system can always replenish its ranks once it emerges from the shell-shock of defeat. Its problem is that it has not been able to refurbish its ideological narrative, let alone offer an alternative one.

Mamata Banerjee can get away with populism because she has not promised anything else. Her challenge is to practice what she preached, but she still has the luxury of time. Not as much time as she or her party thinks, but not as little as the Marxists would wish either. The Marxists, however, cannot be sanguine. When they were in power their threat came from Mamata Banerjee. Now that they are in opposition, the danger to their fortunes is from BJP.

This is the meaning of Narendra Modi’s successful rally at the Brigade Parade Ground in Kolkata. Not too long ago, BJP leaders would be awash in self-congratulation if their enthusiasts filled an indoor stadium. In this election season, saffron was visible at a venue that was once dominated by the red flag and now flies the green standards of Mamata.

The BJP is not a worry for Mamata Banerjee. But the left could cede territory in Bengal if it does not revive, and quickly. We are not talking of any dramatic leap forward; BJP is not going to win too many seats in the state this year. But its rising support will be evident when votes are counted. A political party moves a bit like an army. Defeat can degenerate into collapse if commanders are unable to rally troops in adversity. But any advance can only happen in stages. Marxists thrive on dialectics. They should be able to understand this quite easily.

The Bengal Congress has lost its connect with Bengal. At best, Congress is playing hop-scotch, jumping from one square to another. In the Rajya Sabha elections, it joined forces — unsuccessfully — with the left. Simultaneously, it is sending desperate private messages to Mamata for an electoral alliance on any terms. Beggars, as the proverb puts it, can’t be choosers. If Congress and Left Front MLAs believed that their parties had a chance of victory this year, there would not have been any defection.

The writer is an author and editorial director of The Sunday Guardian, published from Delhi.