Jeremy Corbyn has been a Labour member of parliament and a durable ally to social movements for decades, but when his long-shot candidacy for Labour leader in June 2015 became a landslide reality, it took everyone by surprise. Even more surprising has been his ability to beat back challenges from the Labour right, which included a vote of no confidence in June 2016 and a leadership contest in which Corbyn actually saw his vote share increase. Seeing as how his opponents present themselves as the competent, savvy, and electable wing of the Labour Party, his political success has mystified many, especially in the mainstream media.

But Alex Nunns, author of the newly released The Candidate: Jeremy Corbyn’s Improbable Path to Power, argues that the Labour leader’s success is no fluke. Jacobin’s Duncan Thomas spoke to Nunns to understand the long-term processes that led to Corbyn’s rise and what the future holds for the social movements drawn to him.