The Democratic Party needs to be better prepared. The coming A.I. revolution threatens the urban professional class that constitutes a central pillar of its political coalition — which already seems too small to win a national election. Even some Republicans have managed to sound the alarm, as when Senator Josh Hawley of Missouri helped introduce bipartisan legislation (with Senator Mark Warner, Democrat of Virginia) in November that would require companies to report A.I.-related layoffs. It’s the kind of policy that may resonate with voters whose jobs are in danger. Democrats need to monopolize this issue, lest we risk losing voters we take for granted.