Of the many reasons why Trump's campaign to radicalize white suburbanites against Democrats is doomed to fail is that the white share of the suburban pop has dropped from 93% to 65% since 1970. Plus, the (largely college-educated) whites that remain are overwhelmingly D. So...
The Trump campaign's strategy actually seems remarkably simple right now. They have realized there are not enough rural white voters to get Trump elected again, so they're using the DHS & cops to try to make cities look dangerous and scary again. But this isn't 1970 anymore.
Trump got lucky in 2016. The suburbs in the Midwest are a bit more GOP than they are elsewhere (the coasts, the sunbelt) and so were willing to reluctantly vote for him and against a very unpopular and polarizing Hillary Clinton. That + the rural voters there won him the elec.
This time around, it looks like suburbanites won't be so kind to him. They are demographically more friendly to Democrats and generally aren't as susceptible to the "law and order" rhetoric and white flight campaigns of the mid-to-late-1900s. This simply isn't a tactic for 2020.
Add to all this that Joe Biden performs way better with rural, non-college whites than Clinton ever did and IMO even before you get to state-level polls, the president's position is pretty clearly inadequate.
If you had looked at demographic trends and crosstabs on trade, immigration and elite favorability in 2016, you could have spotted the potential for error in the polls. This time around it doesn't look like like the same path exists (though he could open up another one by e-day).
