It’s an ill wind that is blowing in the Democratic Party’s direction. At the beginning of the year — with President Donald Trump’s approval ratings in steady decline — it was conventional wisdom that Democrats would take control of Congress in November and spend the next two years pursuing, among other things, the president’s impeachment. Then, with the war in Iran further testing Trump’s support, a Democratic win in November became even more certain. But dramatic events can change things, and the growing dominance of the Democratic Party by Democratic socialist candidates is a phenomenon that could be a game-changer....