Biden s Press Secretary Karine Jean-Pierre speaking at a briefing in the White House. AP
"They have turned up with no evidence, none, that he did anything wrong. The president didn't do anything wrong," Biden's Press Secretary Karine Jean-Pierre told reporters.
Jean-Pierre described the impeachment probe focused on the Ukrainian business dealings of Biden's son Hunter as relying on "baseless accusations."
"They have said themselves that there is no evidence. This is a political stunt."
She would not comment on how the 80-year-old president himself had reacted to the launching of the investigation by Republicans in the US House of Representatives.
Biden would "speak to the American people" on his priority, the economy, in a speech in the state of Maryland on Thursday, she added.
The probe comes as Biden faces low poll ratings ahead of a likely rematch with former president Donald Trump in next year's presidential election.
Republican House Speaker Kevin McCarthy bowed to intense pressure from his party's Trumpist right and authorized the launch on Tuesday of an impeachment investigation.
Republican House members accuse Biden, a Democrat, of having "lied" to the American people about his son Hunter's controversial business dealings abroad.
The business dealings in Ukraine and China by Biden's 53-year-old son Hunter while his father was vice president under Barack Obama have been a constant target of Republicans.
Hunter Biden, a recovering drug addict, is currently under investigation by a Justice Department special counsel for possible tax evasion and is expected to be charged by the end of this month on a firearms violation.
However, he has not been charged with crimes related to his foreign business dealings, and no credible evidence has emerged so far that the president was involved in anything illegal.