Prime Minister Liz Truss of Britain campaigned as a tax cutter and champion of supply-side economics, and she won the race to replace her scandal-scarred predecessor, Boris Johnson. Now she has delivered that free-market agenda, and it may sink her government. Four days after Ms. Truss’s tax cuts and deregulatory plans stunned financial markets and threw the British pound into a tailspin, the prime minister’s political future looks increasingly precarious as well. Her Conservative Party is gripped by anxiety, with a new poll showing that the opposition Labour Party has taken a 17 percentage point lead over the Tories. It’s a treacherous […]