US President Joe Biden walks to speak with the press before boarding Air Force One prior to departure from Dane County Regional Airport in Madison

Joe Biden vowed Friday to stay in the White House race and blamed his dismal debate performance on "feeling terrible" due to a cold, as he sought to save his reelection campaign with a make-or-break TV interview.

Joe Biden fended off questions about his mental fitness and electability on Friday in a TV interview meant to draw a line under a disastrous debate performance that triggered calls for him to quit his re-election bid.