Not so long ago, Democrats seemed the party of the future. "Inevitable!" predicted some pundits, for demography is destiny. Moreover, in 2020, Democrats, who had won the popular vote six times in seven presidential elections, swept the popular vote again, by 6 million ballots. And they captured both houses of Congress. The future did seem to be theirs. Progressives dominated the major culture-forming institutions of society -- academia, the media, Hollywood -- not to mention the vast bureaucracy of America's national administrative state. Their core constituencies -- women, the young, Blacks, Hispanics -- were growing as a share of the...