The presidential election has raised an uncomfortable possibility for big American cities, most of them run by Democrats.

Voters in the largest urban counties moved more as a group toward Donald J. Trump since the 2020 election than the nation did as a whole, with eye-popping shifts in New York, Los Angeles, Miami and Boston.

That shift may reflect not just the sour national mood, Democratic strategists and commenters have warned, but a backlash to big cities themselves — their intractable housing costs, their homeless camps and migrant waves, their pandemic-era disruptions and long school closures. Perhaps a rising share of urban voters has rejected all that.

The theory proposes a kind of reverse-coattails effect: that local Democratic governance is dragging down the party nationally.

“It’s hard for Democrats to go out and make the case that we’re the party of good government, and Republicans are the party of chaos, when you have very visual examples of cities that look like they are ungovernable, or haven’t been governed well,” said Lis Smith, a Democratic strategist who has worked on presidential and mayoral campaigns.