When voters are asked which Democratic presidential hopeful has the best chance of defeating President Trump, Joe Biden consistently crushes the competition.

He is seen as the most electable of them all, not for any particular achievements or attributes, but essentially because he is the “least bad” candidate among the largely unimpressive field.

The former vice president has always been known to be gaffe prone, but his blunders over the last week   went well beyond gaffe territory and have left some voters wondering if he has become “too old” to serve.

I consider his remark that “poor kids are just as bright as white kids” to be a gaffe. He would have said something like that ten years ago, even 30 years ago. However, when Biden gave an account of the Parkland survivors visit to the White House, an event which took place in February 2018, it became something else entirely.

Speaking at a gun control forum on Saturday in Des Moines, IA, he told supporters, “I met with them and then they went off up on the Hill when I was vice president.” Later on, he said, “Those kids in Parkland came up to see me when I was vice president,” and then spoke about members of Congress ducking meetings with the students.

The following day, Team Biden’s deputy campaign manager and communications director, Kate Bedingfield, tried her best to mitigate the damage her boss had done. She tweeted, “Wouldn’t it be nice to have a president who consoles Americans in their time of need so often that he sometimes mistakes the timing? But even more so, wouldn’t it be nice to have a president who actually fights to prevent these tragedies?”

Nice try Kate.

If his Parkland comments had been an isolated moment, this wouldn’t be an issue.

But these instances keep piling up. From the moment Biden launched his campaign, questions began to swirl about his ability to endure an 18-month campaign. Below is a clip from his kickoff rally speech.

Earlier this spring, President Trump said Joe Biden is not the political athlete he once was.

(The relevant portion begins at 1:50 in the video.)

We all age at different rates, and while many people retain their cognitive abilities well into their 90s, others begin to lose their sharpness earlier.

A headline over the weekend in The Wall Street Journal read, “The latest missteps by Democratic presidential front-runner give some party activists anxiety over whether he still has the stuff.”

And Democrats need to give some serious thought to this. Biden will turn 77 in November. And should he win the presidency, he would take office at the age of 78. The decline in his mental acuity will have progressed in the interim.

Biden’s performance in the first debate was dismal. He was shredded by Kamala Harris. He appeared weak and people noticed.

Ocasio-Cortez told The New Yorker that Biden’s performance raised questions about his cognitive abilities.

And she was far from alone.

Biden recovered somewhat in the second debate, but his recent week of wall-to-wall gaffes have Democrats concerned.

The New York Times reported that, “Recent interviews with more than 50 Democratic voters and party officials across four states, as well as with political strategists and some of Mr. Biden’s own donors, showed significant unease about Mr. Biden’s ability to be a reliably crisp and effective messenger against Mr. Trump.”

Until Biden announced his candidacy in April, he had been largely out of the public eye since he left office. The difference between then and now is striking. He looks old. He moves old. He acts old.

Maybe he’s no longer the Democrats’ best hope to defeat President Trump.