Using the categories of electoral-vote.com, solid dark shades are for leads in excess of 10% (strong), medium solid shades are for leads of at least 5% but less than 10% (weak), and medium shades around something light gray (this site allows pale shades, but not frames) are for less than 5% (barely). 4% is the usual margin of error, although I would be tempted to say that for such states as Alaska, Montana, and Texas I would assign a bigger margin of error -- 5% or even 6%.
The map, using the criteria of electoral-vote.com but Atlas coloration:
Strong Trump (margin 10% or greater)
Weak Trump (margin 5-9.9%)
Barely Trump (margin under 5%) exact tie -- white
Barely Biden (margin under 5%)
Weak Biden (margin 5-9.9%)
Strong Biden (margin 10% or greater)Note that this is really a projection that takes account of states' electoral histories as well as short-term polling. In contrast to the recent polls that have shown a sharp turn away from Trump in the last two weeks or so, this projection makes the assumption that people who made such a turn away from Trump are at most 'shaky' voters for Biden and are likely to return to Trump as the news becomes less inflamed. So if Biden made recent gains, then how solid are those? Not quite as solid as those ready to vote for him in April, let alone January. That Arizona hasn't voted for a Democratic nominee for President since 1996 and not in a real binary election for President in that state (Strom Thurmond wasn't even on the ballot in Arizona in 1948) or that Texas hasn't voted for a Democratic nominee for President since 1976 matters greatly. That Iowa and Ohio voted for Trump by large margins in 2016 also matters.
https://www.cbsnews.com/2020-us-election-battleground-tracker/?ftag=CNM-00-10abc1fWhile surveying voters across the country is an integral part of the Battleground Tracker, this is more than your typical poll. It's really a big data project. We combine polling, voter files (from L2 Political), U.S. Census data, and historical trends to get a clear picture of what's going on in each state.
Here's how we put together that combination:
We know which candidates different types of voters are supporting from our polling, which includes much larger sample sizes — tens of thousands — than a typical poll;
We know how many people like them are in each state and county, as well as their turnout history, from voter files and Census data;
And we know each state's previous election results, which enables us to anchor our 2020 estimates to recent history.
This approach achieves better estimates in states without as much polling. In 2016, for example, scarce polling in certain states like Michigan or Wisconsin led some to believe they were not as competitive as they turned out to be. That picture might have been improved by considering that these states were full of the same kinds of voters shifting to the Republican Party elsewhere.
We don't know who will change their minds at the last minute -- or how.
