I believe alot of higher-ranking Democrats did see that Biden's cognitive skills were diminished but were afraid to rock the boat and speak up. They're so worried about their own political careers that they don't want to get on the bad side of the President. The real culprits are Biden's wife and kids who were in total denial and encouraged him to seek a 2nd term despite his low approval ratings. Very few people will come out and say it, but Biden was the main culprit the Democrats got their butts kicked in the election, instead people blame Kamala who really had no chance to win as a last-minute replacement. I always considered Biden as a 1 term President because of his age, but greed and his ego got in the way when he decided to seek a 2nd term.