A lot of attention has been paid to the core, fervent base of support that Trump enjoyed from the primaries through the general election. But he won because more-moderate Republicans who were iffy about him ended up voting the party line. They, like a number of independents, didn't really like him, but they liked Hillary Clinton even less.

That's a problem because Trump has seen a big drop in support from precisely those groups. Republicans overall have shed 11 points of support for Trump -- but moderate Republicans have dropped 17 points since January.