A new poll shows that some Democratic voters are deeply concerned about whether Joe Biden is mentally fit to serve as president after a shaky debate performance on Thursday.
A CBS News Youth Gov poll released on Sunday found that 72% of registered voters believe the president does not have the mental and cognitive health to serve as president - a sharp increase from the 65% who said the same in an earlier CBS News poll.
Forty-nine percent of voters say the same of former President Donald Trump

Democratic President Joe Biden's family has urged him to ignore calls to step aside following his disastrous debate against Republican Donald Trump.
He spent Sunday with relatives at a presidential retreat where they encouraged him to keep fighting, according to the BBC's US partner CBS News.
Anxiety has gripped sections of his party following a rambling and at times incoherent performance in Atlanta.
Polls since then suggest concerns about his age - he is 81 - have increased.
A CBS News/You