Wilmington, Delaware - Hunter Biden, the long-troubled son of Joe Biden, went on trial Monday on gun charges in a historic first prosecution of a sitting president's child – and potential threat to his father's reelection.

The only surviving son of President Biden, Hunter Biden is charged with lying about his illegal drug use when buying a handgun in 2018, a felony.

The 54-year-old arrived in court in his hometown of Wilmington, accompanied by family members, including First Lady Jill Biden, although not the president. Jury selection got underway, with the trial expected to last one to two weeks.

President Biden said he and the first lady, who was marking her 73rd birthday Monday, were "so proud" of Hunter Biden.

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"As the President, I don't and won't comment on pending federal cases, but as a Dad, I have boundless love for my son, confidence in him, and respect for his strength," Biden said in a statement.

The trial comes days after a jury in New York made history by finding Donald Trump guilty of business fraud, the first time a former president has ever been criminally convicted.

Trump, who is running as the Republican challenger to Joe Biden in November, faces three other far more serious criminal cases, including his alleged attempt to overthrow the 2020 presidential election.

The Delaware trial – along with another in which Hunter Biden faces charges in California on tax evasion – is an embarrassment for Joe Biden, as he seeks a second term and hopes to keep the country's focus on Trump's behavior.

In addition to being a political distraction, Hunter Biden's legal woes will reopen painful emotional wounds for the family from his lengthy period as a serious drug addict – a period that both he and his father have discussed publicly. Hunter Biden's brother Beau died from cancer in 2015, and his sister Naomi died as an infant in a 1972 car crash.

The Yale-trained lawyer and lobbyist-turned-artist is charged with falsely stating on legal paperwork when buying a .38 caliber Colt Cobra revolver in 2018 that he was not using drugs illegally. He is also charged with illegal possession of the firearm, which he had for just 11 days in October of that year.

Hunter Biden has pleaded not guilty. He had earlier reached a plea deal with prosecutors but this collapsed, leading to the trial.

Prosecutors are set to introduce voluminous – and often uncomfortable – evidence linked to Hunter Biden's years as an addict.

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They have called as witnesses three of his former partners, including Lunden Roberts, the mother of one of his children.

The president's son, who has written unsparingly about his addiction, will contend that at the moment he bought the revolver, he did not consider himself to be an addict. He has stated that he has been sober since 2019.

If found guilty, Hunter Biden could face 25 years in prison, although as a first-time offender, he could get a far lighter sentence or escape any jail time.

President Biden on Monday said that his son's difficulties would resonate widely.

"Hunter's resilience in the face of adversity and the strength he has brought to his recovery are inspiring to us. A lot of families have loved ones who have overcome addiction and know what we mean," he said.

Hunter Biden has long been the target of Trump and hard-right Republicans, amplified by exhaustive coverage on Fox News.

Lurid photos from his time as an addict have been leaked, and Trump allies have investigated him at length in Congress on allegations of corruption and influence-peddling. However, no charges have ever been brought.

Hunter Biden's messy private life and controversial foreign business dealings in China and Ukraine have also formed the basis for attempts by Republicans in Congress to initiate impeachment proceedings against President Biden. Those efforts too have gone nowhere.

The White House said last year that there would be no presidential pardon for Hunter Biden in case of a conviction.

Democratic Congressman Adam Schiff, a Biden ally, told CNN Sunday that Americans should "absolutely" respect the jury's verdict.

"I think the president himself will respect the verdict – much as it is painful, I'm sure, to see one of your children on trial."