The US House of Representatives will open a formal impeachment inquiry into President Joe Biden, its most senior Republican has said.
Kevin McCarthy said the inquiry would focus on "allegations of abuse of power, obstruction and corruption" by Mr Biden.
Republicans have been investigating the president since they took control of the House in January.
The hearings have found no concrete evidence of misconduct by Mr Biden.
They have, however, shed more light on business dealings by the president's son Hunter Biden - which Republicans say are questionable - and on Mr Biden's knowledge of his son's activities.
In a brief statement at the US Capitol, Mr McCarthy said there were "serious and credible" allegations involving the president's conduct.
"Taken together, these allegations paint a picture of a culture of corruption," he said.
The White House was quick to condemn Mr McCarthy's decision.
"House Republicans have been investigating the President for nine months, and they've turned up no evidence of wrongdoing," White House spokesperson Ian Sams wrote in a social media post.
"Extreme politics at its worst."
Hunter Biden is currently under federal investigation for possible tax crimes related to his foreign business interests.
Mr McCarthy, a California lawmaker, also alleged that the president's family has received special treatment from Biden administration officials investigating allegations of misconduct.
The White House has denied any involvement in the Hunter Biden case, and said that President Biden has no ties to his son's business operations.
This inquiry will give congressional investigators greater legal authority to investigate the president, including by issuing subpoenas for documents and testimony that can be more easily enforced in court.
The US constitution states a president can be impeached for "treason, bribery, or other high crimes or misdemeanours", a process which can end in them being removed from office.
However, any effort to remove President Biden would be unlikely to succeed.
The House of Representatives, where Republicans hold a narrow 222-212 majority, would need to vote in favour. It would then need to proceed to a Senate trial and vote.
Democrats have a majority in the Senate, and would almost certainly shoot down the proceedings if it gets that far.
Mr Trump, the only US president to have been impeached twice, was acquitted both times by his fellow Republicans.
Mr McCarthy, who as Speaker leads Republicans in the House, has been lobbied for weeks by right-wing members to open an impeachment inquiry.
Congressman Matt Gaetz of Florida, a close ally of former President Donald Trump, called the announcement "a baby step following weeks of pressure from House conservatives to do more". He had previously threatened to force a vote to remove Mr McCarthy from his leadership position if the Speaker did not start an impeachment investigation.
Mr McCarthy's hold on power in the House has been tenuous ever since he won the top job in January after 15 rounds of voting in the chamber - a modern record.
He is currently trying to shepherd a series of spending bills through the House. These measures must be approved by Congress by the end of September to avoid a partial shutdown of the US government.
Mr McCarthy's move to back impeachment could be viewed as an attempt to curry the favour of right-wing House Republicans ahead of the budget battles.
Such a strategy comes with risks, however. Centrist Republicans in competitive districts have expressed unease with an aggressive impeachment push, worried that it will alienate the independent and moderate voters who carried them to victory.Mr McCarthy has a 10-seat majority in the chamber, so if even a handful of these Republicans have cold feet on impeachment, it could ensure its failure.
Some vulnerable House Republicans told reporters on Tuesday that they are focused on the ongoing congressional investigations into Mr Biden, rather than an impeachment inquiry.
Democratic Senator Chris Coons said in an interview with the BBC, said that "Speaker McCarthy shows that he's being held hostage by the most extreme elements of his Republican majority."
Already Democrats are pointing out that Mr McCarthy sharply criticised Democratic leader Nancy Pelosi in 2019, when she announced an impeachment inquiry into Mr Trump without holding a formal vote.
While Mr McCarthy has only said he is approving an impeachment inquiry at this point, pressure will build for a formal authorising vote in the House to set the rules for impeachment hearings.
Such a vote would put those centrists on the record - and provide fodder for Democratic attacks during the November 2024 general election.
That is a next-year problem for Mr McCarthy, however. For the moment, he is trying to keep unruly conservative members of Congress from openly rebelling - and forcing a vote on whether to remove him from his job.
Impeachment - or at least a movement toward it - could buy him the political breathing room to survive the coming months.