It was a striking setback for a president who proclaimed himself his party’s kingmaker in last year’s midterms, but has a decidedly mixed record when it comes to pushing his chosen candidates to victory in general elections. And it continued a November losing streak that included not only Mr. Bevin’s loss in Kentucky, but a wave of state and local Democratic victories in Virginia, Pennsylvania and Missouri that also were driven by suburban voters.

The results in Kentucky and Louisiana are particularly ominous for the president, in part because they indicate that his suburban problem extends to traditionally conservative Southern states and may prove even more perilous in the moderate Midwest next year.

They also reveal political weakness for the president at a moment he is embroiled in a deepening impeachment inquiry and desperately needs to project strength with his own party. And as he enters what will likely be a difficult re-election campaign, the two states emphatically demonstrated that he has become just as much of a turnout lever for the opposition as with his own supporters.