The Wall Street Journal writes about this.
Reporters asked Harris whether voters' concerns about Biden's age meant she needed to convince them she was ready to serve as president.
“I am ready to fulfill my duties. There is no question about this,” she said.
Earlier, special prosecutor Robert Huhr completed his investigation into Biden's improper storage of classified documents.
In the report, Hoer urged not to bring a criminal case against the American leader, since in court Biden could appear before the jury as a “nice old man with memory problems.”
Politico then said Democrats had warned Biden's aides that he could not back down on the report and should make more public appearances to demonstrate his mental alertness.
According to German magazine Der Spiegel, Joe Biden has begun to appear "weaker and more vulnerable" than ever before during his time in office. Following the release of an investigation into the US president's mishandling of classified government documents, Biden tried to refute perceptions that he was "old and distracted", but instead he confirmed those concerns, the article said.