Both candidates would be 80 years old by the end of their first term if they were elected president.
The top four 2020 candidates are all septuagenarians.
Sanders is 78, Biden is 76, President Donald Trump is 73, and Sen. Elizabeth Warren (D-Mass.) is 70.
Carter, now 95, said on Sept. 17 that he didn’t think he could perform the duties of the presidency if he were 80.
“If I were just 80 years old, if I was 15 years younger, I don’t believe I could undertake the duties I experienced when I was president,” he told the crowd after being asked whether he would consider running for the Democratic nomination. read more