Opinion polls in the United States have long pointed to the strong possibility of a Democratic Party sweep in the election on November 3, with Joe Biden winning the presidency and Democrats gaining control of the US Senate and holding onto the House of Representatives, putting an end to divided government.

But if the election turns out to be mostly a referendum on President Donald Trump, Democrats might win just the White House while failing to retake the Senate. And one cannot rule out the possibility of Trump navigating a narrow path to an electoral college victory, and of Republicans holding onto the Senate, thus reproducing the status quo.