First, do no harm: Joe avoids bloopers that feed Trump’s false mind games

Segregated by social media silos and TV viewing habits that only expose them to like-minded people, many Democrats may not be aware President Donald Trump is seriously campaigning on the idea Joe Biden is senile.

Or worse yet, they may not realize that some people are buying into it.

That’s why job one for Biden on Thursday night at the Democratic National Convention was to do nothing to feed into the narrative questioning his mental fitness.

As silly as it might seem considering he just came out on top of a grueling nomination process, Biden, 77, needed to avoid the flubs that could find their way into the next Trump attack ads or the highlight clips of the president’s Fox News attack dogs.

And except for one slightly mangled line near the end, Biden overachieved with a speech worthy of any presidential nominee.

Dispelling Trump’s big lie clearly had been an unspoken focus of Biden’s handlers during the first three nights of the convention as they sought to showcase their candidate’s mental agility in controlled situations interacting with supporters — albeit via edited video — or informal live settings with his wife Jill.

There’s a big difference, of course, between the verbal gaffes and tongue-tied episodes that have long been Biden trademarks and someone who is actually suffering from dementia, as Team Trump has tried to suggest.

But for those who are looking for an excuse to vote for Trump again, the president’s campaign commercials featuring a blooper reel of Biden’s greatest hits give them something on which they can hang their hats.

The only thing worse than peddling the big lie is accepting it.

It reminds me a lot of how Trump convinced his supporters in 2016 that it was Hilary Clinton who was the corrupt one, which is why Democrats need to take this seriously even if they find it preposterous.

The attack is indeed ironic coming from the 74-year-old Trump, who is prone to his own incomprehensible ramblings.

With Biden, you at least can be comfortable he knows what he wants to say and eventually makes sense, as opposed to Trump, who starts from a place of crazy and never leaves. After four years of Trump’s unhinged Twitter rages, we now know that’s the real him.

It’s true that sometimes Biden’s mouth works faster than his brain, or maybe it’s vice versa.

If he’s elected, I’m sure we’ll have enough material to keep ‘‘Saturday Night Live’’ busy for the next four years, but we’ve got that already without even half of Biden’s decency.