The Democratic primary victory of ultra leftist Darializa Avila Chevalier over Uptown Congressman Adriano Espaillat, pushed across the finish line by Zohran Mamdani, is a dangerous blow for American politics, dragging the party towards its extreme left wing and threatening to destroy the broad coalition that makes for a healthy party and a healthy democracy.The Republican Party has already been ruined by a decade of Donald Trump pumping the extreme right wing and wiping out the moderates and centrists. And Trump did it again on Tuesday, in the most northern reaches of New York State to fill the seat of...