US President Joe Biden boards Air Force One to depart from Philadelphia International Airport in Philadelphia, Pennsylvania, on July 7, 2024. Biden is back out on the campaign trail Sunday, desperate to salvage his re-election bid as senior Democrats meet to discuss growing calls that he quit the White House race. The 81-year-old Democrat kicks off a grueling week with two campaign rallies in the battleground state of Pennsylvania, before hosting the NATO leaders' summit in Washington. (Photo by SAUL LOEB / AFP) (Photo by SAUL LOEB/AFP via Getty Images)