ILMINGTON, Del. — Hunter Biden pleaded not guilty to three charges in a federal courthouse Tuesday, the next step in a long-running investigation that could result in his criminal trial colliding with his father’s 2024 presidential election campaign.

Federal prosecutors accused the younger Biden in a four-page indictment last month of making two false statements in 2018 when he completed paperwork to purchase a gun. Biden asserted on the form that he was not addicted to or using illegal drugs, the indictment says, “when in fact, as he knew, that statement was false and fictitious.” He is also charged with unlawfully possessing the gun.

A plea agreement Biden had tentatively reached with prosecutors collapsed over the summer, offering new ammunition to Republicans who have accused the Justice Department of mishandling the case.

The deal would have had him plead guilty to two misdemeanor tax violations while admitting to illegal possession of a gun, but not actually pleading guilty to that felony offense.

After the deal fell apart, Delaware U.S. Attorney David Weiss — the prosecutor who has overseen the investigation since it started during the Trump administration — asked Attorney General Merrick Garland to make him a special counsel, a designation that would give him clearer authority to bring charges outside of Delaware.

Weiss is now weighing whether to file tax charges against Biden in California, according to people familiar with the matter who spoke on the condition of anonymity to discuss a sensitive case.

Republicans, including former president Donald Trump, have tried to link President Biden to his son’s alleged wrongdoing, and have made the Hunter Biden investigation a focal point of the 2024 presidential race.

Federal law makes it illegal to possess a weapon while using illegal drugs. Hunter Biden has publicly acknowledged being addicted to drugs at the time of the 2018 gun purchase. He allegedly owned the Colt revolver for 11 days.

According to federal sentencing guidelines, Biden could face up to 10 years in prison, though in reality, since he does not have a criminal record and is not accused of a violent crime, he would probably face far less time.

“Hunter Biden possessing an unloaded gun for 11 days was not a threat to public safety, but a prosecutor, with all the power imaginable, bending to political pressure, presents a grave threat to our system of justice,” Hunter Biden’s attorney, Abbe Lowell, said after prosecutors charged his client.

Hunter Biden has publicly acknowledged being addicted to drugs at the time of the gun purchase.