It is a truism that US vice-presidential debates rarely affect the electoral outcome. After Tim Walz’s lacklustre showing against JD Vance on Tuesday night, Democrats will be praying that still holds.

Political betting site Polymarket gave Walz a 70 per cent chance of winning at the start of the debate. By the end he was at just 33 per cent. It will be some consolation that the TV viewing numbers are likely to be far lower than the audience of almost 70mn that tuned into Kamala Harris’s encounter with Donald Trump last month.

Either way, the Vance-Walz debate was probably the last of the 2024 presidential campaign. Trump has shown no interest in agreeing to Harris’s call for a second encounter, understandable given how much blood she drew in their first.