NEWTON, Ia. — Joe Biden, during his second multi-day visit to Iowa this month, placed an increased emphasis on his electability, stressing that he believes he is uniquely capable of defeating President Donald Trump.

Meanwhile, Trump seized on some of Biden's misstatements on the campaign trail to argue that Biden isn't fit for the job. Biden welcomed the attacks, though, which fit neatly into his message.

"As long as they compare me to Donald Trump, it's a good thing," Biden told the Des Moines Register in a one-on-one interview Wednesday. "I tell the truth. It's a big difference."

The former vice president, who is competing for the Democratic presidential nomination, also released a new Iowa television ad targeting Trump and highlighted polls that show him faring well in hypothetical match-ups with the president.

While the other Democratic candidates are good people, Biden told reporters, they don't have the experience on the international stage that he does.

"I think, at this moment in time, I'm the most qualified person to do it," he said Tuesday.

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'The words of a president matter'

On the campaign trail, Biden often says: "The words of a president matter."

He's talking about Trump, whom he has accused of encouraging white supremacy, but at times, it's Biden's own words that have created headaches for his campaign.

Biden has a longstanding reputation for verbal slip-ups. That reputation was borne out earlier this month when he told the Iowa Asian & Latino Coalition that "poor kids" are "just as talented as white kids" before correcting himself.

And, at the Des Moines Register Political Soapbox at the Iowa State Fair earlier this month, he flubbed a closing line of his stump speech by saying "we choose truth over facts."

At a gun-safety forum in Des Moines, he said survivors of a 2018 mass shooting in Parkland, Florida, visited him while he was vice president.

Biden has admitted to misspeaking, but he told the Register that he's not concerned the slip-ups will impact his ability to take on Trump.

"If you call that a gaffe, I accept it," Biden said of the Parkland remark. "But the bottom line is there’s a difference between inciting white supremacy and using language like that and saying, 'when I was vice president.' I was the former vice president in 2018."

Trump and others have seized on Biden's mistakes to question his mental fitness and ability to do the job of president.

"Joe Biden is not playing with a full deck. This is not somebody you can have as your president," Trump told reporters after Biden's comment to the Asian & Latino Coalition.

Supporters say gaffes show Biden is human

Some of Biden's gaffes have become comedic material for him on the campaign trail, like his retelling of his remark to then-President Barack Obama the passage of the Affordable Care Act in 2010 was a "big f---ing deal." Biden's sentiment — and his use of the expletive — was picked up by a microphone.

"I stepped back from the microphone and I whispered in his right ear, thinking he was far from the microphone. I swear there must have been a press person reading my lips over there," Biden joked in Newton.

The retelling invariably gets a laugh, which seems emblematic of how Biden's supporters see his tendency to say the wrong thing.

Tim Weil, a 66-year-old farmer from Prole who saw Biden during a recent visit, called the gaffes "a worry, but very minor."

"You can tell that he’s a very highly intelligent person who thinks rationally. It’s just a quirk that he’s prone to slip-ups like that. It’s not a big deal," Weil said.

Several voters suggested criticizing Biden for misspeaking is unfair, given Trump's stream of controversial remarks and misstatements of facts.

"To me, that’s nothing. Compare him to what we’re dealing with now. That, to me, is the problem. Not a gaffe here and there," said Kelly Tracy, 50, of Johnston, who will serve as a precinct captain for Biden.

Tammy Engel-Meyer, 49, saw Biden give remarks in Urbandale on Tuesday. She's undecided about who to caucus for, but said she's not bothered by Biden's verbal flubs. Her three children, ages 17, 20 and 22, feel differently.

"I know who he is from his record, so that doesn’t bother me," said Engel-Meyer, of Johnston. "But I have three young voters. And I listen to them, and it bothers them."

Message of unity appeals to undecided caucusgoers

In his most recent two-day swing through the state, Biden hit Trump on the economy, trade and immigration and said "we have to unify the country" after the division he accuses the president of causing.

"We're in a situation right now where Donald Trump has decided that he represents his base," Biden told a crowd in Newton. "If I'm your president, I'm planning on representing everybody."

It's a message that appeals to the crowds Biden draws to his events.

Amber Zink, a 38-year-old day care provider from Newton, is undecided but said she tends to prefer moderate candidates and liked Biden's message of unity.

"I like what he had to say about bringing Republicans and Democrats together," she said after seeing Biden in Newton on Wednesday.

Eleven-year-old Lily Duffy spoke to Biden after his event in Newton and told the former vice president that she had recently asked for a bulletproof backpack as she prepared to go back to school.

"We were sitting on the couch the other day, talking about school, and she just said, 'Can I have a bulletproof backpack?' I didn’t know that was even a thing," said Betsy Duffy, Lily's mother.

Lily asked the former vice president what he would do about gun violence. He told her about his efforts to pass an assault weapons ban in the 1990s and said he would continue to work for school safety. Then, as he has before in Iowa, he gave her money for ice cream.

"He's really genuine and kind," Betsy Duffy, 42, of Pella, said, adding she's undecided about who she will support.

Age a concern for some voters

Weil, the farmer from Prole, said he is concerned about Biden's age, but there isn't a younger candidate he likes as much as Biden.

"I'd rather that he be Biden 20 years ago, but the other Democratic candidates are too liberal," Weil said. "Biden has the best chance of being elected — and we've got to get Trump out."

Biden, who is 76, said he has not considered a pledge to limit himself to one term — something that Republican nominee John McCain did in 2008 — but said questions about his age are fair game. He has sought to head off those concerns through displays of energy on the campaign trail, like jogging in Independence's Fourth of July parade.

"Look, it’s a legitimate thing to be concerned about my age, just like it was a legitimate concern when I was 29 whether I had the judgment to be a United States senator. I think it’s totally legitimate," Biden told reporters in Newton. "The only thing I can say is, 'Watch.' 'Watch.' Check my energy level, determine whether I know what I’m talking about, make a judgment. That’s totally appropriate."

Reporters Tyler Jett and Brianne Pfannenstiel contributed to this report.

Stephen Gruber-Miller covers the Iowa Statehouse and politics for the Register. He can be reached by email at sgrubermil@registermedia.com or by phone at 515-284-8169. Follow him on Twitter at @sgrubermiller.

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