Sanders, whose brother is a Green politician in the UK, might be the first openly socialist American to run a serious US presidential campaign since Eugene V Debs in 1920. And Debs did it from a prison cell. Bernie has crashed into this race pledging to raise the highest rate of tax to 90 per cent and socialise health care – yet has jumped to second place in some early primary states and has tons of activist energy behind him. You could dismiss the enthusiasm as an energised fringe. But why is there a fringe to energise at all? Because grassroots Democrats suspect that the Democratic Party has failed by its own progressive standards. Even under Barack Obama – not only black but instinctively liberal – inequality has grown, African-Americans have slipped back and the US government has bombed foreigners and spied on its own people.