The world voiced revulsion Wednesday at the massacre of Texas schoolchildren, which for some raised new questions on whether the United States can effectively promote itself as a global model. President Joe Biden, who has made championing democracy a key priority, appeared conscious of the damage to the US reputation in an impassioned plea for action late Tuesday moments after returning from Asia. “What struck me on that 17-hour flight, what struck me, was these kinds of mass shootings rarely happen anywhere else in the world,” said Biden, who had mourned victims of another mass shooting in Bu…