India finally appears on the brink of rejecting an ideology that most of the world junked a generation ago. For the first time in their history, India's communists are staring at the prospect of extinction. Several polls show the two main parties–Communist Party of India (Marxist) and Communist Party of India–headed for their worst ever performance in ongoing national elections.

Just how badly are the communists doing? According to Delhi's Centre for the Study of Developing Societies, the vote share of the so-called Left Front...