In other words, the state level polls suggest that Biden has a national lead of around 8 points.
EIther way, all methods agree that Biden has a fairly sizable national advantage.
Examining the state polls has the advantage of having a lot more data points to play with, so I feel fairly secure that they’re giving us a decent snapshot. We’re looking at more than 20 polls and more than 15,000 interviews. The aggregate margin of error is small.
Additionally, we can look at states we expect to be at least somewhat competitive (i.e. those where the margin was within 10 points last time) and those that we don’t think will be close in 2020.
In the competitive states (where most of the state polling has been conducted), there has been an average swing of 6 points toward Biden compared to Clinton’s 2016 result. The same is true in the non-competitive states.
At least from this state level data, it does not seem that either candidate is running up the score disproportionately in areas that were already friendly to him.
We can test our data, too, to see what would happen if the polls are underestimating Trump like they did in 2016.
What I found was Biden would still be ahead, even with a 2016 sized mishap.
Concentrating on just the competitive states, the polls undersold Trump by 2 points (RealClearPolitics) or 3 points (FiveThirtyEight). If the polls in the competitive states were off by as much as they were at the end in 2016, Biden would still be ahead in states like Florida, Michigan and Pennsylvania.
The bottom line is Biden’s ahead right now nationally and in the competitive states. The good news for Trump is he has about six months to change the course of the campaign, which is more than enough time to do so.