Speaker Kevin McCarthy launched an impeachment probe into President Joe Biden for what the Republican leader called a “culture of corruption,” stoking partisan passions as Washington barrels toward a potential government shutdown.

The formal inquiry will focus on his son Hunter Biden’s overseas business affairs and whether the president was involved in the dealings or benefited from them, and potentially other topics, a House official familiar with plans said.

Read More: McCarthy Tested by GOP Hardliners From Impeachment to Ukraine

Republican lawmakers also have condemned Biden for “weaponization” of the Justice Department, citing the federal prosecutions of former President Donald Trump for efforts to overturn the 2020 election and of rioters involved in the Jan. 6, 2021, attack on the Capitol.

The California Republican is bypassing a House floor vote to move to an impeachment inquiry, said another official familiar with his thinking. Such a vote would have posed a serious risk for swing-district Republicans and may have failed.

McCarthy was vague on the impeachment probe but asserted there were “serious and credible allegations” against Biden.

The speaker announced the inquiry as House lawmakers returned to Washington from a six-week summer recess.

Funding for the government will run out on Sept. 30. House conservatives are demanding deep spending cuts, an end to “woke” diversity polices in the military, stronger border enforcement and reductions or a halt or reduction to Ukraine aid in order to approve money to keep the federal government operating.

The impeachment announcement quickly stirred praise from Republican hardliners and scorn from Democrats.

Republican Representative Marjorie Taylor Green applauded McCarthy’s “strong leadership.” Democratic Senator Elizabeth Warren dismissed it as “politics on steroids” and “all about Speaker McCarthy bowing down to a handful of extremists who will cost him his job.”

McCarthy faces a near-impossible choice on impeachment. The conservative members who want to continue investigating Biden could move to remove McCarthy as speaker if they are denied. But success is not guaranteed and moving forward will alienate more moderate members and jam up an already-clogged legislative calendar.

If House Republicans succeed, Biden would be the fourth impeached US president. Trump, his predecessor, was impeached twice by the House but not convicted in the Senate.

Republicans have just a 10-seat majority, and 18 House Republicans represent areas Biden won in 2020, including five districts in places like New York and California where incumbents want to campaign on the economy and local issues. Moderate Republicans from those districts, including Brian Fitzpatrick of Pennsylvania and Don Bacon of Nebraska, have expressed concern about proceeding with an impeachment inquiry without strong evidence of wrongdoing by the president.

Read More: McCarthy Tested by GOP Hardliners From Impeachment to Ukraine

McCarthy has said an impeachment inquiry gives House lawmakers stronger standing to demand bank records and other documentation from the Biden family.

He said he has directed Oversight Chairman James Comer to lead the investigation, in coordination with Judiciary Chairman Jim Jordan.

Earlier in the day, the White House dismissed the suggestion that Biden’s actions merit an inquiry.

“Will anyone ask Speaker McCarthy *why* an impeachment inquiry is the “next logical step?,” Ian Sams, the spokesman for the White House counsel’s office posted on X, formerly known as Twitter. “The House GOP investigations have turned up no evidence of wrongdoing by POTUS. In fact, their own witnesses have testified to that, and their own documents have showed no link to POTUS.”

Any effort to impeach Biden would run into deep skepticism in the Senate.

John Thune, the second-ranking Republican leader in the Senate, told reporters Tuesday he doesn’t think “it’d be advantageous” to force a Senate trial of Biden.

“My solution to changing things around here is to win elections, and I think we ought to be focused on that,” Thune said. “But he’s under a lot of pressure” from House Republicans, he said of McCarthy.

--With assistance from Zach C. Cohen, Laura Litvan and Ana Monteiro.