A growing number of polls are showing voters concerned about President Biden's age and energy. Democratic lawmakers have hesitated to offer full-throated endorsements of his running mate. Prominent commentators have ruminated on whether he should drop out of the presidential race.
This series of political vulnerabilities - along with House Republicans announcing an impeachment inquiry and the Justice Department indicting Biden's son on gun charges - is now sending waves of anxiety through parts of the Democratic Party, as some fret about whether the man who helped oust Donald Trump from the White House may not have the vitality, at 80, to successfully prevent a return.