Donald Trump’s 2016 election victory stunned the world. It also uprooted the electoral map: Trump won narrow victories in states which had voted Democratic for decades. This year, many forecasters have been keen to stress the unpredictability of an election that may well redefine that map again.

Holding an election in a pandemic makes predictions tough: while most Republican voters are still happy to vote in person, most Democrats have cast absentee or early ballots – which may be counted at different times or rejected at different rates.