US President Joe Biden said Wednesday he was "not focused" on an impeachment inquiry announced a day earlier by Republican lawmakers, as his White House blasted "baseless" allegations of wrongdoing.

"I don't know quite why, but they just knew they wanted to impeach me," Biden said of the Republican effort.

"I get up every day... not focused on impeachment. I've got a job to do. I've got to deal with the issues that affect the American people every single solitary day," he told attendees at a private campaign fundraiser.

The 80-year-old Democrat's brief remarks were his first public comments on the issue since House Speaker Kevin McCarthy, the top Republican in Congress, bowed to intense pressure from his party's hard right and authorized the impeachment inquiry on Tuesday.

When asked about the investigation earlier Wednesday, Biden's spokeswoman had stronger words.

"They have spent all year investigating the president... and have turned up with no evidence, none, that he did anything wrong," White House Press Secretary Karine Jean-Pierre told reporters.

"That's because the president didn't do anything wrong."

Republican House members accuse Biden of having "lied" to the American people about his son Hunter's controversial business dealings abroad.

But Jean-Pierre said Republicans did not even have enough support for a vote in the House to approve an impeachment probe. 

"Even House Republicans have said the evidence does not exist," she said. "This is a political stunt."

The probe comes as Biden faces low poll ratings ahead of a likely rematch with former president Donald Trump -- who himself was impeached twice by a Democratically controlled House but acquitted in the Senate -- in next year's presidential election.

- 'Good things' -

Biden ignored impeachment questions from reporters at the White House on Wednesday as he led a meeting of his "Cancer Cabinet" which aims to eradicate the disease, part of a recent effort by the administration to put the focus back on his domestic agenda.

Cancer is personal for Biden, whose eldest son Beau died from brain cancer in 2015 at age 46. Biden had a cancerous skin lesion removed in February while doctors removed two from First Lady Jill Biden a month before.

Biden has stood resolutely by his sole surviving son, Hunter, 53.

The younger Biden's business dealings in Ukraine and China 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.

The probe however threatens to distract the White House and give Republicans fresh material for attacks ahead of the November 2024 election.

Biden holds a slim one-percent lead over Trump -- 47 percent to 46 -- in a hypothetical match-up, according to a new national poll by Quinnipiac University.

Half of voters thought Joe Biden was involved in Hunter's business dealings with China and Ukraine, while 35 percent thought the president did something illegal, the poll found. 

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