【明報專訊】THE Democratic Party has regained control of the House of Representatives in the midterm elections of the US. It is inevitable that US President Donald Trump will face more constraints on domestic policy. However, the "blue wave" that the Democratic Party anticipated has not happened. Not only has the Republican Party retained its majority in the Senate, it has won more seats. Both parties seem to have made gains as well as losses as anticipated, but populism is the biggest winner in reality. The recent election has seen the Republican Party embracing rightwing populism as though it has become the "Trumpian Party". As for the Democratic Party, it is also turning towards economic populism. The political ecology of the US is undergoing a fundamental change. It is not easy for it to turn back from populism and protectionism, and there is little hope that the China-US trade dispute will be alleviated.