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DES MOINES, Iowa — Biden’s bumbles are back — and some Democrats are concerned.

Former Vice President Joe Biden delivered a series of verbal fumbles and gaffes during his longest swing to date through Iowa, providing fodder for President Trump’s accusations that he’s slipped mentally and leaving some local Democrats worried that he’s lost a step.

At the Iowa State Fair on Thursday, Biden flubbed a standard campaign line. “We choose truth over facts,” he bellowed, instead of his normal “truth over lies.”

Later that evening at an event with the Iowa Asian and Latino Coalition, he declared that “Poor kids are just as bright, just as talented, as white kids,” before trying to word-salad his way out of the flub: “Wealthy kids, black kids, Asian kids, no, I really mean it, but think how we think about it.”

At the same event, he mentioned former British Prime Minister Margaret Thatcher when he meant to refer to German Chancellor Angela Merkel, before correcting himself. Immediately afterwards, he seemed to attribute a Martin Luther King, Jr. quote President Obama often used to the president himself: “As Barack says, you know, we bent the arc, the curve, toward justice.”

And on Saturday, he told reporters that he was vice president during the Parkland shootings, which occurred a year after he left office: “Those kids in Parkland came up to see me when I was vice president.”

None of the most recent fumbles are likely to prove fatal, and Biden remains the nominal front-runner both in Iowa and nationally, according to polls. But they join a long line of recent verbal slips: at a fundraiser after the El Paso and Dayton shootings, he lamented “the tragic events in Houston today and also in Michigan” (he later corrected himself), and during the most recent debate he told awkwardly told viewers to “go to Joe 30330” (he meant to get voters to text the campaign, not point them to a website). And they prompted some renewed concerns that a candidate with a decades-long penchant for gaffes is struggling to keep his message tight.

“It’s dangerous territory, obviously. It plays into the narrative that Donald Trump would like to create about him,” said Grant Woodard, a Des Moines-based Democratic power player and former congressional chief of staff. “His greatest asset in this race is he’s perceived to be the most electable in the general election and these unforced errors he creates undermine that argument.”

Other Democrats in the state privately expressed concerns about Biden’s gaffes and what they meant, though many didn’t want to take potshots on-record to fuel a narrative they saw as beneficial to Trump.

“Joe’s too old,” one unaligned Iowa Democratic official told VICE News.

Biden and his team shrugged off the string of stumbles.

“Look, I misspoke,” Biden said when asked about his “white kids” comment, during the same press gaggle where he made his Parkland comments. “On the spot, I explained it.”

“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 will actually fight to prevent these tragedies?” tweeted Biden spokeswoman Kate Bedingfield.

Some Democrats rolled their eyes at the questions about Biden’s flubs.

“It is truly horrific that we live in a country with so many school shootings that probably all of us at one point or another get confused about which one happened when,” Iowa State Auditor Rob Sand (D) told VICE News.

Sand said that press coverage off gaffes can actually help candidates who are perceived for speaking their minds: “It wins Biden — and Trump, when it happens to him — sympathy points when everyone writes stories about things that don’t really matter when everyone knows what that person meant to say.”

But Trump and his team have looked to score points off the flubs and push the narrative that Biden is slipping mentally.

His campaign blasted out Biden’s “white kids” comment accusing him, somewhat ludicrously, of racism. Trump himself mocked Biden’s “facts” comment, tweeting “Does anybody really believe he is mentally fit to be president?”

Trump himself is a gaffe machine. In prepared remarks after last week’s shootings, he referred to Toledo instead of Dayton. He churns out a steady stream of typos, misspellings, and errors on Twitter to accompany his racist rhetoric and verbal attacks on opponents, like his retweet over the weekend of a conspiracy theory tying Jeffrey Epstein’s death to Bill and Hillary Clinton. During his 4th of July speech this year, he said that during the American revolution, troops “took over the airports.”

Gaffes are nothing new for Biden. His 1988 presidential campaign collapsed in large part because he failed to attribute a story he was telling on the stump to another politician, a plagiarism scandal that seems quaint by today’s politics standards. And his hot-mic whisper to President Obama ⁠— that passing Obamacare was a “big fucking deal” ⁠— is now part of Biden lore.

“We all hear this and think about it and are concerned about it. But is this really different in your mind of the Joe Biden of old? He’s always been known for speaking with gaffes,” former Iowa Lt. Gov. Patty Judge (D) told VICE News. “Back when he ran before, certainly the eight years he was vice president, there were numerous times we all had a chuckle at Joe. I’m not sure he’s any different than he always has been, there’s just a huge lens on him right now.”

Read more: Biden takes shots from all sides in debate.

The bigger problem for Biden is not whether he gaffes more often and worse than Trump — it’s how he stacks up in a crowded field of eloquent candidates, many of them decades younger than him. Trying to clean up his missteps without losing his authentic-seeming charms will be difficult for Biden.

Some of Biden’s primary foes have made some minor verbal stumbles as well in the past — Bernie Sanders made a similar comment conflating being poor and being black in 2016, for instance. But Biden stands out for his regular verbal misfires.

“The problem is that he is a part of a field of a number of extremely articulate people. He and his campaign are going to have to work hard to try to articulate their message without those kinds of gaffes. … [and run] a vigorous campaign in order to counter the idea that he’s too old ” said Judge. “But that’s just part of Joe. We’ll see how it all shakes out.”