The US president's son Hunter Biden pleaded not guilty to federal charges on Wednesday after a plea deal collapsed..In the surprise development, a disagreement arose with prosecutors over a gun charge..Biden was expected to plead guilty to two tax charges under a deal with the government..However, the judge delayed ruling on the agreement until she “receives additional information.”.The case will reconvene at a “future date,” which some speculate could be within the next four to six weeks..The outcome of Wednesday’s hearing leaves open, at least temporarily, the years-long investigation into Biden's business dealings..Hunter Biden was charged with two tax crimes of failing to pay more than $100,000 in taxes from more than $1.5m in income in 2017 and 2018..An agreement with prosecutors, who planned to recommend two years of probation..Now that deal has collapsed..Last month, he was charged with possession of a firearm by a known drug user, a felony..It was reported that Hunter had a Colt Cobra .38 Special for 11 days in October 2018..He, therefore, agreed to enter into a diversion agreement, which means that he would not technically plead guilty to the crime. The charge carries a maximum sentence of 10 years in prison..“I think having you guys talk more makes sense,” said US District Court Judge Maryellen Noreika, suggesting the lawyers discuss it..Noreika said she was concerned about the language in the diversion agreement..US President Joe Biden has said very little publicly about the case and the allegations against his son, except, “I’m very proud of my son.”