The chairman of the House intelligence committee has said he is temporarily stepping aside from the panel's probe into Russian meddling in last year's US presidential election.
The decision by Devin Nunes, of California, comes amid partisan turmoil on the committee.
Democrats have alleged that Republican Mr Nunes, who was on President Donald Trump's transition team, is too close to the White House and cannot lead an impartial inquiry.
"Several left-wing activist groups have filed accusations against me with the Office of Congressional Ethics," Mr Nunes said in a statement.
"The charges are entirely false and politically motivated, and are being levelled just as the American people are beginning to learn the truth about the improper unmasking of the identities of US citizens and other abuses of power."
Mr Nunes did not disclose details of the allegations.
House Speaker Paul Ryan said he supported Mr Nunes's decision and said the congressman is eager to talk to the ethics panel.
"It is clear that this process would be a distraction for the House intelligence committee's investigation into Russian interference in our election," Mr Ryan said.
He said he believes it is in the best interests of the committee and Congress to have GOP representatives Mike Conaway, of Texas, with help from Trey Gowdy, of South Carolina, and Tom Rooney, of Florida, to temporarily take charge of the investigation while the House ethics committee looks into the issue.
"I will continue to fulfil all my other responsibilities as committee chairman, and I am requesting to speak to the ethics committee at the earliest possible opportunity in order to expedite the dismissal of these false claims," Mr Nunes said.
He said he is confident that Mr Conaway will oversee a professional investigation into Russia's actions and follow the facts wherever they lead.