India, Nov. 10 -- The victory of Zohran Mamdani, a democratic socialist, in the historic New York mayoral election is not only a challenge to Donald Trump but also to right-wing political leaders worldwide. His triumph demonstrates that it is possible to unseat far-right, authoritarian leaders who, through their politics of hate, exclusion, arrogance, and hyper-nationalism, have created havoc not only in their own countries but also beyond their borders.

At 34, Mamdani-a Democrat born to Indian and Ugandan immigrants-is poised to become the first Muslim mayor of New York City, as well as the first of African descent and of South Asian heritage to hold the office. When he takes office on January 1, he will also be the youngest mayor in ov...