WASHINGTON — Congressional Republicans lodged a formal case Monday for the impeachment of US President Joe Biden, using the opening day of the Democratic National Convention to launch a political assault unlikely to gain serious traction.

The report from three powerful committees in the Republican-led House of Representatives accuses Biden of corruption linked to his son Hunter’s foreign business affairs.

Republican Rep. Jim Jordan of Ohio, the head of the Judiciary Committee, said the probe showed “conclusively” that Biden had “abused his public office for the private financial benefit of the Biden family and Biden business associates.”

“President Biden’s legacy is marked by abuse of public office, corruption and obstruction. The evidence produced by our impeachment inquiry is the strongest case for impeachment of a sitting president the House of Representatives has ever investigated,” said Republican James Comer, the Kentucky congressman who heads the House Committee on Oversight and Accountability.

However, there is no proof that Biden ever used his office to benefit his son or was involved in Hunter’s businesses. There was no smoking gun in a document built around inferences and innuendo about connections between father and son.

Biden — set to deliver a swan song speech at the Democratic convention in Chicago on Monday, and pass the political torch to his vice president Kamala Harris — has repeatedly denied helping his son’s business ventures, including in Ukraine and China.

Republicans have for years used Hunter Biden’s foreign links and chaotic personal life as a recovering drug addict to try and embarrass the president.

However, marathon attempts to build an impeachment case against Biden — seen by many as a bid for revenge over the two impeachments of Republican Donald Trump when he was US president — have never come close to an actual vote by the House.

Republicans hold only a razor-thin majority and would likely fail to remain unanimous on impeaching Biden, risking severe embarrassment.