Boone, Iowa (CNN) As Joe Biden worked his way down the rope line at the Boone County Fairgrounds Friday, his campaign was dealing with what has become a routine problem.

The Trump campaign had seized on Biden's mix-up of two words during the previous night's speech -- and that fit neatly into Trump's narrative that the 76-year-old former vice president isn't equipped for the mental rigors of the presidency because he's not "playing with a full deck."

Biden knew the questions were coming. But here in Boone, he was in the zone, relaxed and seemingly untroubled as he offered well wishers his skilled hand as they squinted in the bright sun, trying to position their iPhones for selfies with "Uncle Joe." It's an ease that comes of years of experience, with both crowds and scrutiny -- and one that he intends to use as he continues to make his case for the White House.

"He's just a regular guy, just like us. Wants the best for our country and our people, and that's what we all want," said Shelby Grabau, who described herself as a 28-year-old stay-at-home mom who works with special needs students during the year. She and her friends were much more interested in Biden's message about rebuilding the middle class -- which he describes as his "North Star" -- than his gaffes

Biden locked eyes with Gary Craven, who told the former vice president that he'd recently lost his 48-year-old son Todd after a struggle with alcohol withdrawal.

"The (Veterans Administration) failed him," Craven, a Boone resident, said in a recounting of their conversation to CNN. He added that his daughter recently retired from the Air Force — after stints in Iraq, Afghanistan, Jordan, Korea and Somalia—with a medical discharge due to post traumatic stress disorder.

"She saw too much," Craven said.

Biden leaned in close, gripping Craven's shoulders.

"Can I get your number and call you?" the former vice president asked him. An aide dutifully took down Craven's number and said Biden would call him from the car.

A little ways down the rope line, a reporter shouted a question about Thursday night's word mix-up — in which Biden misspoke by saying "poor kids are just as bright and talented as white kids" before immediately correcting himself. President Donald Trump's daughter-in-law used the mix-up to question his mental acuity, the reporter noted.

"Tell them it's the second anniversary of Charlottesville coming up, so they need to divert to something," Biden replied, referring to the fatal street violence that occurred at the 2017 Unite the Right rally in Virginia. Biden often rebukes the President's handling of the incident -- Trump's perceived encouragement of white supremacists with his response that there were "very fine people on both sides" -- while campaigning.

The reporter persisted: "Are you able, do you think, to go through a whole campaign with this kind of scrutiny on you?"

"Yes, I have to, it's legitimate scrutiny," Biden replied. He turned back to the Iowa woman who was trying to take a picture with him: "Fire away."

"Mr. Biden, they say these gaffes ding your electability ," another reporter interjected.

"Well, that's going to be determined pretty soon, isn't it?" Biden parried back. He kept moving down the line, handing a $20 bill to a little girl named Maci Grabau for ice cream, telling her he "owed her big" for being so good as she listened to his entire speech under the hot sun.

Craven, the father Biden promised to call, dismissed the attention to the former vice president's so-called gaffes.

"He's a human being like the rest of us, instead of just a Democrat," Craven said when asked why he isn't seriously considering any of the other Democratic candidates. "I've read his book. I've listened to him speak going as back as far as the Obama campaign. I worked 40 years as an electric utility lineman, a foreman, and I understand that experience counts. And some of these people, I don't believe have reached the level of experience to where they can handle the job that Trump is going to leave us."

He continued: "I didn't think it was possible for one man to destroy the fabric of this country. I'm just a fat, old retired guy from the Midwest, but I just throw my hands up (with Trump). I think that Joe, from what I've seen and read, is probably the finest man who has ever served in our government."

"His book -- the part about Beau -- I had to put it down quite a few times," Craven said, referencing Biden's late son who died of brain cancer in 2015.

Voters connect with Biden

The words that Biden speaks about division, discord and polarization connect with voters like Grabau and Craven. In his speech in Boone, Biden noted that his opponents attack him for being delusional and naïve -- a critique he finds ironic considering his age compared to others in the field. He went on to note that he wants to unite the country; that he believes in his heart that the American people don't want the division that Trump is sowing.

All of the Democratic candidates in the presidential field say something along those lines. The difference is that Democratic voters leaning toward Biden know his history over many years, and see him as the kind of guy who could do some of that healing.

That was apparent as Biden campaigned throughout Iowa this week with more than a few voters approaching him seeking comfort. At the Iowa State Fair on Thursday as Biden made his way to the soapbox to deliver his speech, he stopped to enfold a grieving grandmother from Carroll, Iowa, in a hug after reading on her T-shirt that she was trying to get her grandson out of foster care.

"We're going to bring him home," Biden told Melody Nelson in that brief encounter. Her voice caught in her throat as she described their exchange to a reporter a few minutes later.

"I love him and Obama," Nelson, 56, said. "I hope he does great here. And I will do whatever I can to help him win."

Biden on the trail

There is no question that Biden shows his age more now than when he was running with Barack Obama. It comes to mind not only with his occasional word flubs, but when he strains to summon the right phrase in his speeches. And it's not yet clear how effective Trump will be in softening Biden's support with his attempts to describe him as "Sleepy Joe" or lacking "a full deck."

Biden's campaign is clearly taking care to address what could become a dangerous liability for his campaign. When he spoke outdoors at the Boone fairgrounds on Friday, for example, he used a teleprompter and frequently referred to his notes as he made his way through his speech -- perhaps cognizant that another mistake would be unhelpful as his rivals attempt to build the narrative that he's too old for the job.

And still, mistakes were made over the weekend. At a gun control forum on Saturday, he said twice that he met with students who survived the shooting in Parkland, Florida. The issue: The incident happened in February 2018, more than a year after he left office.

But in comparison to a 73-year-old President who eschews exercise and seems to prefer riding around in a golf cart to walking, Biden walks at a clip that sometimes makes it difficult for the throng of reporters and cameras to keep up.

With a tone that is reminiscent of his close friend, the late Republican Sen. John McCain, Biden is quick with witty retorts as he brushes off questions about his age. At the fair and during the march to the Wing Ding, he'd occasionally break into a jog -- in one case to run over and introduce himself to a man in a red Trump 2020 T-Shirt: "There's a lot to be hopeful about," he said to the surprised Trump supporter as they shook hands.

In Clear Lake, Iowa, he broke from his press pack in the parking lot of the Wing Ding dinner to jog over and say hello to the tent of Kamala Harris supporters in their yellow T-shirts. One told him she had worked for him and President Obama.

"God love ya," he replied.

He also displays what can only be described as a kind of grandfatherly concern for the people around him.

"Watch the pole!"

"Don't back into that car!"

"There's a rock on the right!"

"Watch out for the kids behind you!" he'd yell out to the photographers and photojournalists who were walking backwards to keep their cameras trained on him as he moved through the fair.

When his worst fear came to fruition and a photographer did in fact stumble backwards over a couple of young boys in baseball caps, Biden came to a dead stop in his Ray-Bans, hands on his hips and his mouth tensed in a tight line of frustration.

After pausing for that moment, he walked over to the kids.

"I'm so sorry that happened," he told them. "You guys OK?" he asked before chatting them up about their favorite attractions at the fair.

And, amid the swarms of media, he snapped at a reporter who repeatedly asked him whether he believed Trump was a white supremacist.

"Why are you so hooked on that? You want me to say the words so I sound like everybody else," Biden told the reporter. "I'm not everybody else. I'm Joe Biden. I've always been who I am. I'm staying the way I am. He is encouraging white supremacists, you can determine what that means. It's like everybody wants everybody to call someone a liar. When you say -- 'I don't call people liars. I say they don't tell the truth.' You want to hear me say 'liar,' so you can put it out and say Biden called someone a liar. That's not who I am. You've got the wrong guy."

It was one of the many times Biden displayed that air of confidence that only comes after decades in politics — the knowledge that there will be ups and downs, and the occasional reminder to aides and reporters that this isn't his first rodeo.

When he arrived at the fair 20 minutes early and his staff was trying to move him toward the soapbox, the former vice president glanced at his watch and looked perplexed. "We're just going to stand there at the soapbox for 20 minutes?" he asked his aides.

He made an executive decision. There was time for ice cream. Natch.