Here’s why: Several of Trump’s worst demographic groups happen to be concentrated in states, such as California, New York, Texas and Utah, that are either not competitive or that aren’t on Trump’s must-win list. Conversely, whites without a college degree — one of Trump’s strongest groups — represent a huge bloc in three blue states he would need to turn red to have the best chance of winning 270 electoral votes: Florida, Ohio and Pennsylvania.

A repeat of 2000’s split verdict — except with more potential to plunge this much more polarized and anxious country into chaos — is still not very likely. Right now, the FiveThirtyEight polls-only model posits a 6.1 percent chance of Trump winning the Electoral College while losing the popular, and a 1.5 chance of the reverse outcome. But that’s not so remote, either, and if the national ballot were ever to tighten further, both “crazy” scenarios’ odds could rise.

The secret to how Clinton could win more votes nationally yet still fall short of the White House lies with Trump’s weakness among three geographically disadvantaged groups of voters…