Alabama’s voters have shocked the Republican Party, energised Democrats and alerted an attentive world to the possibility of political change in the United States by electing the radical liberal Doug Jones to the US Senate instead of the white nationalist Roy Moore. The special election was extraordinarily polarised between white and black voters, with high turnout reflecting Moore’s toxicity to large parts of the electorate. It is a welcome result but does not necessarily herald similar changes in next year’s congressional races and the 2020 presidential vote.

Donald Trump supported Moore only after he had won the primary contest, with strenuous backing from Stephen Bannon, the former chief White House strategist. Bannon’s war with the Republican establishment is exemplified by this contest and Moore’s failure to take the seat may tip the balance in forthcoming ones. That will make a real difference as both main parties prepare for the 2018 congressional elections. The Democrats hope to shift the Republicans’ Senate majority, now reduced to 51-49, while they need to win 24 seats to control the House of Representatives. The Alabama result gives them greater confidence after winning the Virginia and New Jersey governorships last month.

Whether the Democrats turn this result to advantage will depend not only on their own efforts but on how the Republicans respond. Trump’s electoral base responds to his appeal to white nationalism and economic protection. The real cleavage between that base and the Republican establishment is highlighted by their responses to Alabama. In the short term, their joint congressional efforts are geared to getting through the major tax reform Bill before Doug Jones takes his seat in the new year, threatening their Senate working majority.

The Bill hugely benefits richer Americans at the expense of the poorer whites. But, as Lyndon Johnson famously observed in the 1960s, “If you can convince the lowest white man he’s better than the best coloured man, he won’t notice you’re picking his pocket. Hell, give him somebody to look down on, and he’ll empty his pockets for you.” Democrats will also be aware of how Trump can turn stronger economic performances to advantage. US statistics show 3.3 per cent growth, unemployment at 4.1 per cent and the Dow Jones index up 24 per cent since last year.

Forthcoming elections will be determined by Trump’s economic record and how the nation’s wealth is distributed, as well as by the dramatic racial and gender issues thrown up in the Alabama result. If the Democrats are to turn this opportunity to their advantage against Trump they will need to find a more effective formula to bring these issues together.