Will Joe Biden’s early poll lead in the Democratic Party primaries be a blessing or a curse?

Politics Explained: Donald Trump came from nowhere to become the Republican candidate in 2016, but the Democratic field for 2020 has less potential for surprises

Logic should dictate that paying significant attention to polling about the 2020 Democratic primaries almost nine months before they begin is folly.

But if precedent is anything to go by, the current state of the polls can give some useful indications about how the general election could look next November.

You just need to add the Donald Trump-mandated caveat that history was already upended in 2016.