Even on the placid streets of London’s Mayfair, James Carville cannot find peace. “Every five minutes I get stopped and asked about Chuck Schumer,” says the Democratic strategist when I speak to him. “I can’t even enjoy a $30 martini by myself.”

Carville’s party is in dire straits. The humiliation of losing to Donald Trump had not yet worn off when the Donald stormed back to the White House with a vengeance, unleashing the chainsaw-wielding Elon Musk on the federal government, assembling a cabinet intent on carrying out even his most radical policies – and scaring the few Republican would-be dissenters...