The White House has said President Donald Trump believes he has the power to fire Special Counsel Robert Mueller.
"We have been been advised that the president certainly has the power to make that decision," said Press Secretary Sarah Sanders when asked if Mr Mueller could be fired.
The statement came a day after FBI agents raided the offices of the president's personal lawyer, Michael Cohen, acting on a "referral" from Mr Mueller, who is investigating suspected Russian meddling in the 2016 election.
Politicians from both sides of the US political divide have urged the president to allow Mr Mueller to continue his work.
Mr Mueller was appointed by the Justice Department in May 2017 to take over the FBI's Russia probe after Mr Trump fired FBI Director James Comey.
However, US House Speaker Paul Ryan said he has been assured by the White House that Mr Trump does not intend to fire Mr Mueller or Mr Rosenstein over their Russia probe.
"I have no reason to believe that that's going to happen," Mr Ryan said at a news conference.
"I have assurances that it's not, because I've been talking to people in the White House about it."
White House lawyers Ty Cobb and Donald McGahn are said to be trying to dissuade Mr Trump from seeking to get rid of Mr Mueller, saying it would leave him vulnerable to charges of obstruction of justice, but have made little or no progress persuading the president, according to two US officials.
Aides said Mr Trump was fuming yesterday over the raids but his future course of action remained unclear.
The advice of the lawyers takes on greater significance following the departure of key aides, such as Hope Hicks, who recently resigned as White House communications director.
Mr Trump has called Mr Mueller's probe a "witch-hunt".
A TOTAL WITCH HUNT!!!
— Donald J. Trump (@realDonaldTrump) April 10, 2018
Attorney–client privilege is dead!
— Donald J. Trump (@realDonaldTrump) April 10, 2018
"The raid is seismic," Democratic Senator Richard Blumenthal, a former federal prosecutor, told MSNBC, adding such searches by the FBI indicate the possibility a crime was committed.
