US PRESIDENT JOE Biden’s son Hunter has pleaded not guilty to two tax crimes after a plea deal with federal prosecutors unravelled during a court hearing following the judge’s concerns over the agreement.

Hunter Biden was charged last month with two misdemeanour tax crimes of failure to pay more than $100,000 in taxes from over $1.5 million in income in both 2017 and 2018, and he made an agreement with prosecutors, who were planning to recommend two years of probation. That deal is now on hold.

During the hearing today, there was a dispute in court over whether the initial agreement gave him protection against any future charges.

US District Court Judge Maryellen Noreika, who was appointed by President Donald Trump, raised concerns about the language of the deal.

The judge gave defence lawyers and prosecutors 30 days to explain why she should accept the initial deal.

This collapsed the proceedings, a surprising development because the plea had been carefully negotiated over weeks and included a lengthy back-and-forth between Justice Department prosecutors and Biden’s attorneys.

The plea deal was meant to clear the air for Hunter Biden and avert a trial that would have generated weeks or months of distracting headlines.

But the politics remain as messy as ever, with Republicans insisting he got a sweetheart deal and the Justice Department pressing ahead on investigations into Trump, the Republican 2024 presidential primary front-runner.

Prosecutors said in court that Biden remained under federal investigation.

Judge Noreika raised multiple concerns about the specifics of the deal and her role in the proceedings.

The plan also included an agreement on a separate gun charge — Biden has been accused of possessing a firearm in 2018 as a drug user.

As long as he adhered to the terms of his agreement, the gun case was to be be wiped from his record. Otherwise, the felony charges carries 10 years in prison.

The overlapping agreements created confusion for the judge, who said the lawyers needed to untangle technical issues — including over her role in enforcing the plea deal — before moving forward.

“It seems to me like you are saying ‘just rubber stamp the agreement, Your Honour’. This seems to me to be form over substance,” she said.

Meanwhile, Trump is already facing a state criminal case in New York and a federal indictment in Florida.

Last week, a target letter was sent to him from special counsel Jack Smith that suggests the former president may soon be indicted on new federal charges, this time involving his struggle to cling to power after his 2020 election loss to Joe Biden.

Republicans claim a double standard, in which the Democratic president’s son got off easy while the president’s rival has been unfairly castigated. Congressional Republicans are pursuing their own investigations into nearly every facet of Hunter Biden’s dealings, including foreign payments.

Today, the judge asked Biden to be more specific about his business relationships and to discuss his substance use issues as she combed through the plea agreement. She asked him to name the Ukrainian and Chinese entities referred to without name in the agreement.

She also asked him the last time he used alcohol or drugs and whether he was currently receiving treatment.

Biden answered June 1 2019 and said he was not currently in treatment, though he did say he was in an anonymous support programme for his substance issues.

President Joe Biden, meanwhile, has said very little publicly, except to note, “I’m very proud of my son.”