He recently referred to mass shootings in Houston and Michigan instead of El Paso and Dayton, mixed up former British prime minister Margaret Thatcher with Theresa May, and told minority voters that "poor kids are just as bright and just as talented as white kids."
"We choose truth over facts!" the former vice president boomed this month at the Iowa State Fair.
Team Biden on Friday was grappling with the fallout from his latest verbal blunder, a retelling last week of a heroic account of a US war hero in Afghanistan.
Biden's telling to a rapt New Hampshire audience was compelling. But many details were inaccurate, as Biden conflated elements of three events into a single storyline.
Biden staffers have repeatedly stressed that part of their boss's appeal stems from his long history of speaking his mind, and Biden himself said it was "ridiculous" to consider his war-hero account a gaffe.
But as the 76-year-old maintains his lead among Democrats seeking to challenge President Donald Trump, and as missteps mount, Biden's propensity for putting his foot in his mouth is coming under greater scrutiny.
"And there will be more, because @JoeBiden is a gaffe and embellishment machine," David Axelrod, a senior advisor to then-president Barack Obama when Biden was vice president, predicted on Twitter after Biden's account about pinning a medal on a US soldier in Afghanistan was reported in detail by The Washington Post.
But the master political strategist said Biden's account, the core of which he believes to be true because Biden did award a medal to a reluctant war hero who lost a comrade, "also reflects something that is a real strength, and that is his empathy."
Biden's ability to connect with voters is undeniable, particularly with people who, like him, have experienced personal tragedy.
His gaffes have always been a part of his allure, baked into the character of a relatable politician equally at ease negotiating with world leaders and chatting with train conductors.
But the mis-speaking has had major consequences. Biden ended his 1988 presidential run when it was revealed that he lifted quotes from a British politician without sourcing them.
- 'Gaffe machine' -
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In recent months his comments have raised fresh alarms. He has appeared out of touch in the Me Too era, joking about his too-tactile behavior.
And he told donors in June that he "got things done" with avowed segregationists with whom he served in the US Senate.
Biden himself has appeared eager to downplay voter concerns.
"I'm not going nuts," Biden quipped to a New Hampshire crowd last week, making light of his failure to recall the location of his speech.
Robert Boatright, chair of the political science department at Clark University, said Biden's gaffes fit into a longstanding narrative that could lead voters to question his fitness and advancing age, especially when the rigors of campaigning may lead to more missteps.
"There's a story about Biden's gaffes that has built up, and it's hard to see how doing a lot of campaigning doesn't run the risk of reinforcing that," Boatright said.
But how much will Biden's flubs matter in the era of Trump, who according to The Washington Post's ongoing research has uttered more than 12,000 falsehoods since early 2017?
Several voters have said Biden's slips of the tongue play little part in their choice of candidate, and his deputy campaign manager seized on a CBS report Friday from South Carolina that reflected such sentiments.
"It's not just that they're not bothered - every voter asked about gaffes in this story talks about how @JoeBiden is real, has heart and understands them," Kate Bedingfield tweeted.
Trump himself has eagerly seized on the slip-ups. After one Biden miscue this month, the president told reporters that "Joe is not playing with a full deck."
Last December Biden acknowledged his shortcoming, but turned it into a knock against the president.
"I am a gaffe machine," he said in Montana. "But my God, what a wonderful thing compared to a guy who can't tell the truth."