Gun control and environmentalism. It's the same reason why Gore lost TN, AR, MO and WV. In the 90s gun control and environmentalism became hot button issues and the Mid Atlantic backed both. The NYC/NJ/CT suburbs back gun control.
The Clinton/Gore administration also signed the environmental agreement, the Kyoto Protocol which also was popular in the region.
But it's not like Dems have softened on gun control and environmentalism relative to the GOP since 2000, and yet they've lost a lot of ground with WWC voters in these states. (And it didn't start with Trump; many of these towns swung substantially to Bush in 2004 and didn't really swing back to Obama in 2008.) This is why I hypothesize that 9/11 may have had some lasting effect, perhaps by reinforcing the GOP's image as the "macho" party and making issues like gun control lose salience.
What he's saying is that environmental issues and gun control are less important issues today than they were in 2000 (though there are still two of the most important issues to me, and the two issues where I am most left-wing). It makes sense in some ways, since Gore was a known environmentalist. Still, overall I feel there might be something else at play here. CT at least should care more about gun control now than it did in 2000 after the Sandy Hook shooting, where first graders were killed, and the GOP declined to offer anything more meaningful or substantial than empty "thoughts and prayers." (Though CT probably voted blue partly because Liebermann was from there.)
