Hunter Biden
© AFP via Getty ImagesHunter Biden appeared confident arriving at a Delaware federal courthouse Wednesday with his โ€œsugar brother,โ€ attorney Kevin Morris
First son Hunter Biden pleaded not guilty to federal tax and gun charges Wednesday, a dramatic about-face after his wrist-slap, probation-only plea deal fell apart Wednesday over his demand for blanket immunity from accountability for all criminal conduct โ€” including alleged illegal foreign lobbying.

The stunning turn of events came more than 90 minutes into the hearing at the federal courthouse in Wilmington, Del., where Hunter was expected to plead guilty to two misdemeanor counts of willful failure to pay taxes and enter a diversion program on a felony federal weapons charge.

Prosecutors admitted under questioning from US District Judge Maryellen Noreika that President Biden's 53-year-old son still could be charged with offenses including failing to register as a foreign agent for lucrative dealings in countries such as China and Ukraine that allegedly involved his father.

"As far as I'm concerned, the plea agreement is null and void," defense attorney Chris Clark reportedly told the court in response a little before noon.

Both sides then tried to move forward with a revised plea deal that specified Hunter would face no additional charges linked to tax crimes from 2014 to 2019 โ€” or any counts involving his drug use and associated gun ownership crimes. However, Noreika indicated she needed more information about the new deal, forcing the first son to enter a pro forma plea of not guilty before the hearing was adjourned.

House Speaker Kevin McCarthy (R-Calif.) has since Monday teased the opening of an impeachment inquiry into President Biden for his alleged role in Hunter's business dealings and the stark confirmation of an ongoing foreign-agent investigation by the Delaware US attorney's office could spur on House investigators.

Hunter Biden introduced his dad to many of his foreign associates and in some instances served as a liaison to US officials. Legal experts assess that he likely violated the Foreign Agents Registration Act through conduct documented on his abandoned laptop and other records.

One of Hunter's closest business partners, Devon Archer, is expected to testify to Congress next week that the then-second son often put his then-vice president father on speaker phone while meeting with overseas partners.

FARA can carry stiff penalties, and a five-year statute of limitations means that charges likely would have to come soon for Hunter โ€” who left the board of Ukrainian gas company Burisma in 2019 and whose most lucrative Chinese government-linked partnership spanned 2017 and 2018.

Violations of the law can send perpetrators to prison. Former President Donald Trump's 2016 campaign chairman Paul Manafort was sentenced in 2018 to 60 months behind bars specifically for FARA violations related to his work in Ukraine, plus another 30 months for tax and bank fraud and witness tampering.

Hunter's legal team said last month that it believed his criminal liability is resolved by the plea deal, but Delaware US Attorney David Weiss said that his office is still conducting an investigation and his team confirmed the ongoing nature of the probe Wednesday.

The first son thus far has avoided charges for allegedly working as an unregistered foreign agent and congressional Republicans are demanding to know what if anything Weiss' team did to investigate an FBI informant's June 2020 tipoff that a Ukrainian oligarch said he paid $10 million in bribes to Hunter and then-Vice President Joe Biden to influence US government policy.

There is evidence that Joe Biden met in person with Hunter's associates from China, Mexico, Kazakhstan, Russia and Ukraine โ€” in addition to meeting with his American partners โ€” and that Hunter complained in records on his abandoned laptop he had to give "half" of his income to his dad.

Hunter also rode aboard Air Force Two with his dad on an official trip to China in 2013 as he set up a state-backed investment fund called BHR Partners, whose incoming CEO Jonathan Li met VP Biden in Beijing. Joe Biden later wrote college recommendation letters for Li's children.

As part of a later Chinese business venture with CEFC China Energy, Hunter and his associates in May 2017 penciled in a 10% cut for Joe Biden. The elder Biden allegedly met with Hunter's business partners in that deal and was listed as a participant in a late 2017 call about CEFC's attempt to purchase US natural gas.

Hunter also flew the taxpayer-funded jet to Mexico in 2016 with business associate Jeff Cooper as he courted that nation's business elite, whom his father had hosted the preceding year at the official vice president's residence in Washington.

The House Oversight Committee in May identified nine Biden relatives who allegedly received foreign income from shady figures in China and Romania โ€” and has argued they were selling access to their powerful relative.

Before the stunning near-collapse of the plea deal, Biden had appeared confident ahead of his hearing Wednesday, showing up alongside his "sugar brother," attorney Kevin Morris.

Morris, a Hollywood-based lawyer and Democratic donor, was spotted last week outside his Los Angeles home while Hunter, a recovering drug addict, paid a visit.

Hunter Biden agreed last month to plead guilty to failing to pay at least $100,000 on more than $1.5 million in earned income in both 2017 and 2018.

He also agreed to admit to lying about his crack cocaine use on a federal firearm purchase form in 2018.

He faced a maximum sentence of two years' probation for the tax crimes and 10 years in a federal prison for lying on the gun purchase form.

Under the diversion agreement for the gun charge, Hunter would have to remain sober, submit to drug testing, avoid committing other crimes for two years and agree not to own a firearm again.

Morris, who accompanied Hunter to court, has been a central โ€” and mysterious โ€” figure in Hunter's orbit since they met at a December 2019 Biden fundraiser.

He reportedly loaned Hunter about $2 million last year to pay off back taxes in a bid to reduce the likelihood or severity of charges for allegedly evading about $2.2 million in tax payments on $8.3 million in foreign income from 2014 to 2019.

As Hunter cried poverty to reduce child support payments to his 4-year-old daughter Navy Joan Roberts, he used Morris' private jet in May to travel to a court appearance in Arkansas.

Morris is also among the buyers of Hunter's novice artworks, according to a Monday report by Business Insider.

And a purportedly leaked business record says he assumed control of Hunter's 10% stake in Chinese state-backed investment fund BHR Partners, which drew negative headlines and questions about conflicts of interest for Hunter and his dad.

IRS supervisory agent Gary Shapley, who led the tax fraud investigation of Hunter for more than three years, suggested in a recent Fox News interview that he was skeptical about the relationship between the men.

"Well, to say [Hunter Biden] paid [back taxes] is a misnomer, right? Because it was an individual, Morris, that he met at a campaign finance event and then he immediately starts giving Hunter Biden money to pay off tax debts, to pay living expenses," Shapley said.

"The money that was given to Hunter Biden by Morris showed up on his tax returns as a loan to him. So, when you have a person that you meet at a campaign finance event, then he's, all of a sudden, giving you millions of dollars and... it's a loan to you, I wouldn't necessarily say that the subject paid those taxes."

Hunter Biden's plea deal has been derided by Shapley, primary IRS case agent Joseph Ziegler, and Republicans in Congress as a "sweetheart" deal.

President Biden's Justice Department appointees allegedly blocked more serious charges while prosecutors allegedly impeded standard investigative steps and barred agents from asking about the president's role in foreign dealings in countries such as China and Ukraine, despite communications that implicate him.