US Attorney General Jeff Sessions has said he will step aside from a federal investigation into Russian interference in the 2016 presidential election.
Mr Sessions faced mounting pressure from both Democrats and Republicans to withdraw after revelations that he had twice talked with Moscow's US envoy during the presidential campaign.
Mr Sessions's conversations with the ambassador seem to contradict his sworn statements to Congress during his confirmation hearings.
The Justice Department said there was nothing improper about the meetings and Mr Sessions insisted he never met Russian officials to discuss the campaign.
Mr Sessions said this week he would recuse himself - or step aside - when appropriate.
When attorneys general have recused themselves in the past, investigations were handled by lower-ranking but still senior political appointees within the Justice Department.
Mr Sessions rejected any suggestion that he tried to mislead anyone about his contacts with the Russian, saying: "That is not my intent. That is not correct."
The attorney general said he made his decision after his staff recommended that he recuse himself from any investigation related to the Trump campaign, since he had been involved in that campaign.
Mr Sessions added that his announcement "should not be interpreted as confirmation of the existence of any investigation",
The White House has stood behind Mr Sessions, though officials said they first learned about his contacts with the ambassador from a reporter on Wednesday night.
President Donald Trump said he had "total" confidence in him and did not think he needed to step aside from the investigation.
The Justice Department has maintained there was nothing improper about Mr Sessions's contacts or his answers to Congress, while the continuing allegations of Russian interference in American politics spurred Democratic calls for Mr Sessions not only to recuse himself but to resign.
He has faced increasing demands that he resolve the seeming contradiction between his two conversations in the summer and autumn with Moscow's US envoy, Sergey Kislyak, and his sworn statements to Congress in January, when he said he had not had communications with Russians during the campaign.
Calling for him to resign, House Minority Leader Nancy Pelosi accused him of "lying under oath".
Senate Democratic leader Chuck Schumer said a special prosecutor should be appointed to examine whether the federal investigation into the Kremlin's meddling in the US election - and into possible contacts between Trump associates and Russians - had been compromised by Mr Sessions. Democrats also sought a criminal perjury investigation.
"If there was nothing wrong, why don't you just tell the truth?" Mr Schumer said. Sessions's testimony "was definitely extremely misleading to say the least", he added.
More than a half dozen Republican lawmakers, including some who consider themselves personally close to Mr Sessions, urged him to recuse himself from the Justice Department probe.
They included Senator Tom Cole of Oklahoma, who said that though he found it impossible to believe that Mr Sessions could have colluded with Russia, "if there is an investigation, he probably shouldn't be the person leading it".
Mr Sessions told a news conference he did not intend to mislead but he "should have slowed down and said 'but I did meet with one Russian official a couple of times'".
Acting Deputy Attorney General Dana Boente will handle any matters related to the investigation.
Behind the scenes at the White House, U.S. President Donald Trump's daughter Ivanka was a key advocate for the more measured, less combative tone he struck in his speech to a joint session of Congress on Tuesday night, officials said.