Biden's former golf instructor takes a swing at Trump's game: 'I like the president's chances'

As Joe Biden and Donald Trump continue to trade barbs over their fitness for office, an unexpected area of dispute has gripped the presidential contest: golf.

Trump teed off on Biden during the recent presidential debate, scoffing, "He can't hit a ball 50 yards."

"I'd be happy to have a driving contest with him," Biden shot back.

"I'm happy to play golf if you carry your own bag. Think you can do it?" Biden added in an exchange that sparked a barrage of jokes on the internet.

Then at a campaign event on Tuesday, Trump challenged Biden to an 18-hole match, offering to pay $1 million to a charity of Biden's choice if he wins.

While Trump, who owns several golf courses and hits the links on a regular basis, might be the odds-on favorite in such a match, there's one golf pro who likes Biden's chances: Earl Cooper, a golf instructor who previously gave Biden lessons.

Golf is "a great way to unveil the individual's character, because it is one of the few sports that is solely relying on you," Cooper, who is also the cofounder of modern golf apparel company Eastside Golf, said in an interview with ABC News.

Cooper, who was approached by Ron Olivere, the father of Beau Biden's widow, to give Biden golf lessons in 2015, told ABC News that Biden "wanted to get better at golf."

"It was something that I appreciated because he took it very seriously," Cooper said. "It wasn't just a showman thing."

Cooper, a former PGA professional with the Wilmington Country Club in Delaware, where Biden is a member, confirmed that Biden once held a single-digit handicap -- a claim Trump questioned during the debate.

"[Biden] was shooting in the 70s, which is good -- a single-digit handicap is a really good golfer in general," Cooper said.

During the debate, the candidates' golfing gloating occurred after they started trading jabs about their physical fitness.

When asked by CNN's Dana Bash to respond to voters who have concerns about his ability to serve through the end of a next term, when Trump would be 82, Trump touted his accomplishments on the links.

"I'm in very good health. I just won two club championships, not even senior, two regular club championships," Trump said. "To do that, you have to be quite smart and you have to be able to hit the ball a long way. And I do it. He doesn't do it."

"I've seen your swing, I know your swing," Trump later needled Biden.

At Thursday's NATO press conference, Biden jabbed back at Trump.

"And where's Trump been? Riding around in his golf cart, filling out his scorecard before he hits the ball?" Biden said of the former president, who's previously been accused of creative scorekeeping on the course.

According to Cooper, Biden -- who drove his own golf cart -- enjoyed playing golf at the country club "because it was the only time that he could drive himself."

"Secret Service [was] driving him everywhere," Cooper said. "So this was the one time that he could get in a golf cart, and drive himself."

Cooper said that, after watching the CNN debate, "There's no doubt [Biden] is slowing down" -- but he still believes Biden could beat Trump in a golf match.

"I like the president's chances, because I know golf, and I'm not sure about his competitor following all the rules," Cooper said.

The Biden campaign this week addressed Trump's golf challenge, releasing a statement that read in part, "Donald Trump hasn't been seen in public for 12 days, now he's ... challenging the President of the United States to golf."

"Donald Trump is ... only out for himself," the statement said. "Par for the course."