Scene set for US presidential campaign

United States President Donald Trump characterised this week’s midterm elections as a referendum on himself. Some voters duly gave him a political black eye while others opted for a rousing ‘‘Atta boy, Mr President’’.

What happened on Tuesday and what does it all mean? First, the Democrats won the House of Representatives for the first time in eight years. They did so in challenging circumstances, including many House races taking place in electoral districts drawn (in some cases gerrymandered) by Republicancontrolled state governments. (In fact, court decisions were needed to create fair electoral maps in Florida, North Carolina, Virginia and Pennsylvania.)

Moreover, 317 of the 435 electoral districts swung towards the left, and although Democrats flipped only 30 of these, there was a drift to the left among many voters in districts the Republicans held. In short, the Dems’ performance is better than it looks at face value.

This means the conservative legislative agenda is dead in the water. Also, Democrats will use congressional committees’ powers of subpoena to investigate issues the previous House did not pursue, including the president’s taxes, ethics and corruption scandals surrounding senior administration figures, and the intertwining of Trump’s business interests and the presidency. As one commentator put it, Democrats now have the power to make Trump’s life hell.

Conversely, Republicans have tightened their control of the Senate. This will make it easier for them to confirm conservative judges to lifetime positions (122 slots on federal court benches are up for grabs) as well as other Trump nominees (including the next Cabinet secretaries). But repeal of Obamacare and further tax cuts are beyond the Republicans, because the Senate cannot pass bills without the approval of the Democratic House.

Third, the Democrats also made some gains at the state level. Last week Republicans controlled 33 of the 50 governorships – today they hold 26. That’s nearly a 50:50 split and it matters because in the US voter eligibility is administered at the state level. Since 2013, 24 states have tightened these requirements. This year, for instance, Georgia, put 53,000 voter registrations (most from black citizens) on hold, while its ‘‘exact match’’ requirements are held responsible for significant voter disenfranchisement. (Weirdly, that system was administered by Georgia’s secretary of state, Brian Kemp, who was also the successful Republican candidate for the governorship. That’s like having Alicia Wright, our Electoral Commissioner, standing for elected office and refusing to relinquish her day job.)

What’s more, in 37 states congressional redistricting (the drawing of electoral boundaries) is also a political process. This happens once every 10 years or so, and last occurred in 2010, when Republicans held the whip hand in state governments. The next redistricting process begins in 2020, meaning Democrats’ gains at state level this year will help shape the next decade of congressional and presidential elections.

Finally, standing back from the detail, it is clear that the midterms have had a profound impact on levels of political energy. Final turnout will be among the highest ever and voters returned a Congress that better reflects the sprawling population of the US. More women were elected than ever, for example, and they include the first Native American and Muslim congresswomen.

There is a possibility, however faint, that the outcome will be bipartisan co-operation. After all, it is in Trump’s interests to cooperate – because if Democrats’ legislation is obstructed by the Senate they will turn their attention to the only other thing they can: oversight of the president. But you wouldn’t bet your House on it.