David Axelrod says former Vice President Joseph R. Biden’s behavior throughout the Democratic Party’s primary process is something akin to watching “Mr. Magoo” cartoons.

The host of CNN’s “The Axe Files” — and former adviser to President Barack Obama — balked on giving Mr. Biden a ringing endorsement for his debate performance Wednesday at Tyler Perry Studios in Atlanta, Georgia.

“Biden, I wouldn’t say he was a house of fire in any of the debates that we’ve been to,” Mr. Axelrod said, Newsweek reported. “And yet he comes … kind of bumps along, kind of Mr. Magooing his way through this. You keep worrying he’s going to hit a wall, but he’s moving forward.”

Mr. Biden appeared at times to struggle with finding and articulating his thoughts.

“I think Biden has the best chance of beating Trump,” MSNBC’s Joe Scarborough responded Thursday morning. “I do. Like, if he’s on his game. But I just wonder, is the media grading Joe Biden on a scale? Are we afraid to say that a lot of his sentences don’t make sense? That he’s having trouble completing thoughts? That when he’s asked in a previous debate about Afghanistan an issue he knows more about than anybody — not only on that stage but in Washington, D.C. — he ends up stumbling through an answer on Iraq. Are we grading him on a scale the same way people have always graded Donald Trump on a scale in these debates?”

Mr. Biden insisted Wednesday evening that he is the candidate who could get a Senate majority for Democrats by campaigning in states like Georgia and North Carolina.

“You have to ask yourself up here: Who is most likely to be able to win the nomination in the first place, to win the presidency in the first place? And secondly, who is most likely to increase the number of Democrats in the House and in the Senate,” Mr. Bidensaid.