Well with Harris waiting in the wings, that might not be a good thing.
And this could come back to haunt him, which would leave her with the main prize:
Opinion: It’s fair to speculate whether Biden is mentally fit to be president
After a disastrous performance in his first debate with Walter Mondale, many in the media began to openly question the then-73-year-old Ronald Reagan’s mental fitness. Writing in the New York Times, James Reston pointed out
that Reagan “got his figures mixed up, and didn’t seem to be mentally alert in dealing with Mr. Mondale’s arguments.” The Wall Street Journal noted
that “the president’s rambling responses and occasional apparent confusion injected an unpredictable new element into the race” and pointed out that at age 75, "10 percent of people suffer from significant mental impairment — senile dementia, or senility.” The networks ran montages of Reagan stumbling over his words and brought on doctors to discuss the effects of aging on mental capacity.
When the second debate came around, Reagan put the aging question to rest with his now famous line: “I will not make age an issue of this campaign. I am not going to exploit, for political purposes, my opponent’s youth and inexperience.” A decade later, Reagan announced
to the world that he had Alzheimer’s disease.
Joe Biden is 77, four years older than Reagan was during the 1984 campaign. If Biden is elected, he’ll be older on the day he takes
office than Reagan was on the day he left
office. So yes, his mental fitness is a legitimate issue.