Joe Biden and Jimmy Carter's decades-long friendship will be on display one last time as Biden eulogizes Carter during his state funeral at Washington National Cathedral.

As a member of the elite, informal club of U.S. presidents past and present, Jimmy Carter was uniquely positioned to do important work for his successors, whether Democrat or Republican

But when asked whether he would have been in a position to serve as president for another four years, Biden conceded he wasn’t sure. “I don’t know,” he told USA Today’s

President Biden acknowledged concerns about his age, stamina and ability to have served a second term in an interview with USA Today in the Oval Office.

President Joe Biden has conceded that he may not have had the stamina to last through a second term in office. “So far, so good, but who knows what I’m going to be when I’m 86 years old?” he told USA Today in an interview published Wednesday.