It's too soon to say whether last week's Republican convention made any dent in the polls. But it did make clear President Donald Trump's chief line of attack going forward: After months of drifting between calling Joe Biden senile or soft on China, Trump and Republicans have settled on recasting him as a "Trojan horse for the radical left" who would promote lawlessness and disorder, "abolish" the suburbs and crash stock markets.

It's an admission that Trump needs to distract attention from voters' top concern — COVID-19. And Trump's rhetorical fusillades against "Democrat-run cities" are a tell of a fall strategy heavy on pumping up his base from 2016: small-town, working-class white voters.

So far this summer, Biden has polled spectacularly well in suburbs — even historically GOP ones in the Sun Belt — thanks to his strength among college-educated white voters.