 The age of both Mr. Biden and former President Trump did come up during last night's debate. White House correspondent Greg Hudson is in Atlanta. Here at the CNN presidential debate, Trump declared his physical and mental fitness for office. I took two tests, cognitive tests. I think I'm in very good shape. And Joe Biden said he's demonstrated his ability to serve as president. Look at the record. Look what I've done. But the president's forced voice and halting delivery likely reinforced voters' concerns about his age.