Democratic front-runner Joe Biden has survived a series of poor debates, weathered criticism that he is out of touch and gaffe prone to still maintain a lead in a majority of the polls. But it's the tangled tale of his middle child Hunter that threatens to scuttle the former vice president's third bid for the White House.

In Democratic circles, there have been whispers for years that Hunter Biden could become a liability for his father. Questions about the younger Biden's overseas business dealings in Ukraine and China as well as his checkered past at home -- he dated his brother's widow, used cocaine, bought crack and allegedly spent so much money in strip clubs and on prostitutes that his family couldn't pay their bills -- has made him an easy target for President Trump.

Trump, who is facing an impeachment inquiry, has aggressively gone after chief rival Biden and his family. Some accusations the president has lobbed can be proved. The majority cannot.

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What's true is that Hunter Biden has become a punching bag for the White House and Trump's closest allies. The 49-year-old's controversial decision to accept a high-paying position at a gas company in Ukraine with little to no experience has become the backdrop of a whistleblower complaint against Trump and is reshaping the 2020 presidential race. Trump has repeatedly accused Hunter Biden of ethical lapses and profiting off his famous father's last name -- something Trump's own children have been widely criticized for doing.

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Earlier this week, Trump tweeted, "Where's Hunter? He has totally disappeared! Now looks like he has raised and scammed even more countries! Media is AWOL."

The social media hits against the Bidens made by a sitting president have been relentless and somewhat shifted the focus of the investigation against Trump to an attack on Hunter Biden.

On Tuesday, the younger Biden finally broke his silence, acknowledging in an ABC interview that his last name likely played a role in getting a lucrative Ukraine gig while his father was vice president and handled the Obama administration's Ukraine policy. However, he strongly pushed back on growing criticism from Republicans and the White House that he was unqualified for the positions he held on several boards.

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Hunter Biden argued that despite a lack of Ukraine or natural gas industry experience he "had as much knowledge as anybody else on the board, if not more."

When Hunter Biden joined the board of the gas company a half-decade ago, its owner, a former Ukrainian government minister working to rebuild Burisma Holdings' image, was facing a money-laundering investigation. In fact, the region was so rife with corruption that one of Hunter Biden's investment firm partners at the time ended his business relationship with Biden. Despite warnings of corruption, Hunter Biden stayed on and pulled in $50,000 a month, Newsweek reported.

His colleagues at Burisma included chairman Alan Apter, who had nearly three decades of experience under his belt at Merrill Lynch, Renaissance Capital, Troika Dialog and Morgan Stanley. Devon Archer, who was appointed as director of Burisma in 2014, co-founded Rosemont Seneca Partners with Biden. He also served as a senior adviser to John Kerry and co-chaired the National Financial Committee.

There have also been concerns about Hunter Biden's dealings with BHR (Shanghai) Equity Investment Fund Management Company. Trump and his personal attorney Rudy Giuliani claimed that Biden used his father's position as vice president to secure $1.5 billion in loans for the Chinese private equity company, where he was a board member. There is currently no credible evidence to support the theory.

Still, earlier this week Joe Biden pledged that no members of his family would engage in foreign deals if he were elected to be president.

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"Look, my son's statement speaks for itself," Biden said, adding that he never acted improperly based on payments his son was receiving from several multinational companies.

While father and son have denied any wrongdoing, Hunter Biden's overseas business dealings and drama stateside have had an impact on Biden's bid for the White House.

"Did I make a mistake? Maybe in the grand scheme of things. But did I make a mistake based on some ethical lapse? Absolutely not," Hunter Biden said during the ABC interview.

The powerful politician's son's woes back home have put him in the spotlight for years. And though he's been open about his drug and alcohol abuse, his bio reads like a tabloid tale, sometimes almost too out there to believe.

Hunter Biden got his law degree from Yale Law in 1996. He returned to Delaware to help his dad who was running for reelection in the Senate. and was tapped to be Biden's deputy campaign manager. He also was a lawyer with MBNA America, a banking holding company in Delaware, which happened to be one of the biggest donors to his father's campaign.

At the age of 43, Hunter Biden applied for and received an age waiver to join the Navy Reserve after being inspired by his friend Greg Keeley, an Australian-American former military officer. Keeley wrote him a letter of recommendation. The Navy has a zero-tolerance drug-and-alcohol abuse policy and asks all recruits about their prior substance use. Hunter Biden disclosed that he had used drugs in the past but said he was sober and got a second waiver from the Navy to join.

In early 2013, Hunter Biden, who had been sober for a couple of years, suffered a relapse after he was prescribed painkillers for shingles. When his prescription ran out, he began drinking again, The New Yorker reported.

On May 7, 2013 he was assigned to a Reserve unit at Naval Station Norfolk. He had hoped to work in naval intelligence but was given a job in a public affairs unit.

During his first weekend on duty, Hunter Biden stopped by a D.C. bar. He said he bummed a cigarette from two South African men and that he felt "amped up" at first but then exhausted as he made the three-hour drive to Norfolk. On his first day as a Navy reservist, he had a routine urine sample taken. A couple of months later he got the news that he had failed the drug test and that trace amounts of cocaine had been detected, The New Yorker reported. He was formally discharged on Feb.18, 2014.

In August 2015, Breitbart reported that Hunter Biden had set up an account on Ashley Madison, a website that connects married people who want to have affairs. The site was hacked and a list of subscribers was made public. Biden vehemently denied setting up the account and said that the profile that used his email address did not belong to him.

"I am certain that the account in question is not mine," Biden said. "This account was clearly set up by someone else without my knowledge."

Two months later, Hunter Biden and his wife Kathleen, who he married in 1993, separated. On Dec. 9, 2016, she filed for divorce. On Feb. 23, 2017, Kathleen filed a motion in D.C. Superior Court seeking to freeze Hunter Biden's assets. She claimed in a motion that was leaked to the New York Post that her husband had put the family on the brink of financial ruin by spending massive amounts of money on drugs, alcohol and prostitutes. Kathleen also dropped the bombshell that Hunter was dating Hallie, his late brother Beau's widow.

Hunter Biden denied paying for prostitutes and claimed he hadn't been to a strip club in years. However, in an act of defiance, he told The New Yorker that the night after the Post article was published he "went directly to a strip club. I said, 'f--k them.'"

As his divorce was playing out in public, his relationship with Hallie started to crumble.

"All we got is sh-t from everybody, all the time,'" The New Yorker reported him as saying.

In 2016, Hunter Biden was supposed to go to a wellness center in Arizona but instead stayed in Los Angeles for about a week. In L.A. he purportedly asked a homeless man in Pershing Square where he could buy crack. Hunter told The New Yorker that the man took him to a nearby homeless encampment where someone put a gun to his head before realizing Hunter Biden was a prospective customer. After that incident, Hunter Biden said, he returned to buy more crack a few more times that week.

While in L.A., Hunter Biden also lost control of his rental car, damaged it and ended up calling the rental agency.

Hertz employee Zachary Romfo claimed he found a crack pipe in the car as well as a line of white powder residue on one of the consoles. Hertz notified the police and a narcotics offense report was filed. The report listed the items seized from Hunter's car, which included a plastic baggie containing a white powdery substance, a Secret Service business card, credit cards and Hunter Biden's driver's license.

His messy personal life complimented his complicated professional life.

On Aug. 23, 2008, then-Sen. Barack Obama publicly introduced Joe Biden as his running mate. Hunter Biden claimed that during the primaries some of Obama's advisers had been criticizing him to reporters. He told The New Yorker that he wasn't told to end his lobbying activities but that he knew "the writing was on the wall."

Hunter Biden dropped his lobbying clients and stepped down from an unpaid seat on the board of Amtrak.

"I wanted my father to have a clean slate," Hunter Biden said. "I didn't want to limit him in any way."

Since then, the younger Biden has been in the spotlight and his past actions have come back to haunt him and his father.

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He told The New Yorker that recently he had seen reports on Twitter that Trump was calling for him to be investigated by the Justice Department. Hunter Biden said he noticed a helicopter flying above and purportedly told his wife Melissa, whom he married in 2019, "I hope they're taking pictures of us right now. I hope it's a live feed to the president so he can see just how much I care about his tweets."

He added, "I told Melissa, 'I don't care. F--k you, Mr. President. Here I am, living my life'."