PORTLAND, Maine—China has failed to live up to its promise to buy more Maine lobster, Maine’s congressional leaders say. Maine’s lobster industry was hurt by retaliatory Chinese tariffs in 2018 and failed to see substantial export gains after China committed to buying an additional $200 billion in U.S. goods, the delegation contends. Under the “Phase One Agreement,” China was supposed to increase purchases above 2017 levels but China has bought “almost no lobster above 2017 levels,” according to a letter Thursday by Maine Sen. Angus King, an independent, and Reps. Chellie Pingree and Jared Golden, both Democrats. They urged U.S. Trade Representative Katherine Tai to “hold China accountable for its purchase commitments.” Republican Sen. Susan Collins of Maine earlier sent a letter voicing the same concerns and urging “swift and appropriate action.” Maine’s live lobster sales to China fell in the year after the lobster tariff was imposed in July …