The harrowing images appalled even the president’s staunchest supporters, many of whom — like a majority of the American public — support the decision to remove American troops from Afghanistan. But some of them worry the execution of the withdrawal has undermined Mr. Biden’s central campaign promise to restore a steady hand to governance, particularly on issues of national security.

Interviews with more than 40 Democrats, lawmakers, strategists and party officials show a White House at a pivot point. If the virus continues to worsen or the situation in Afghanistan deteriorates further, many of the president’s allies fear he will lose the confidence of the moderate swing voters who lifted his party to victory in 2020. Already, Democrats in battleground districts have been sounding alarms that the party needs to become more aggressive with their messaging, particularly on the economy and the efforts to combat the surge in coronavirus cases fueled by the highly contagious Delta variant…

“It’s been deeply disappointing to see the lack of empathy communicated,” said Ms. Stone, who also sits on the board of Indivisible, a national network of local liberal groups. “There’s a profound disconnect between President Biden’s remarks and the images women are seeing on TV and social media of Afghan women and girls in need.”