Jeff Sessions has denied Donald Trump’s tweets were influencing his decisions as it emerged he may launch an investigation into Hillary Clinton corruption allegations.
Mr Sessions, the US attorney general, said Mr Trump is “bold and direct” in expressing his views but promised his decisions would be based on facts alone.
He attempted to play down the row by denying he had been "improperly influenced" by the US president and admitting such behaviour would be "wrong".
It followed the revelation that Mr Sessions is considering appointing a special counsel to look at topics linked to Mrs Clinton, the Democratic presidential candidate who lost to Mr Trump.
They include allegations of corruption against her charitable foundation and the Russian sale of a company with access to US uranium when she was secretary of state.
In a separate development, it has been reported the FBI is investigating almost $400,000 worth of payments from the Russian foreign ministry possibly linked to the US election.
Many of the mystery payments contained the line “to finance election campaign of 2016”, including one of almost $30,000 sent to its embassy in Washington DC.
Some 60 wire transfers to Russian embassies from Afghanistan to Nigeria were being looked into, the website Buzzfeed reported. It is unclear for what the money was intended.
In recent weeks Mr Trump has repeatedly tweeted his anger at the Justice Department’s failure to investigate Mrs Clinton and the Democrats.
The intervention triggered controversy because the US president traditionally does not influence who the department chooses to investigate.
Mr Sessions, a stalwart in Mr Trump’s campaign, has also become the target of the US president’s anger for his failure to stop the Russian links investigation.
I have not been improperly influenced and would not be improperly influenced
Jeff Sessions, the US attorney general
It has led to speculation about Mr Sessions’s political future, with some congressmen wondering if he wants to return to the Senate.
Appointing a special counsel into Clinton-linked topics would counterbalance another special counsel, Robert Mueller, who is ruthlessly pursuing an investigation into Trump campaign links with Russia.
That investigation has dogged Mr Trump’s early premiership and resulted in criminal charges for three of his former campaign advisers.
Earlier this month Mr Trump said: "The saddest thing is that because I'm the president of the United States, I am not supposed to be involved with the Justice Department."
He also said: “I am really not involved with the Justice Department. I'd like to let it run itself. But honestly, they should be looking at the Democrats.”
Government lawyers confirmed Mr Sessions was considering launching a special counsel into Clinton-linked issues and other topics in a letter to a congressional committee.
Appearing before the committee on Tuesday, Mr Sessions denied the decision had anything to do with Mr Trump’s tweets or comments.
“I have not been improperly influenced and would not be improperly influenced,” Mr Sessions said, adding that Mr Trump is “bold and direct” in his views but playing down his influence.
He also said that the Justice Department should “never be used to retaliate against political opponents”, saying that such an approach would be “wrong”.
Mr Sessions was also grilled about his earlier claim that he was not aware of any Trump campaign figures attempting to contact Russian officials for a meeting.
....People are angry. At some point the Justice Department, and the FBI, must do what is right and proper. The American public deserves it!— Donald J. Trump (@realDonaldTrump) November 3, 2017
It has since emerged that Mr Sessions was present at a meeting when a campaign foreign policy adviser, George Papadopoulos, talked about reaching out to the Russians.
Mr Sessions said he “pushed back” on the suggestion, adding that Mr Papadopoulos was “not authorized” to reach out to the Russian government on the campaign’s behalf.
Separately, it emerged Donald Trump Jr, the US president’s son, had messaged WikiLeaks, the transparency body that released Mrs Clinton’s hacked emails, during the campaign.
Mr Trump Jr tweeted a link to leaked Democrat documents published by WikiLeaks just days after being provided the url by the group, it emerged.
He has since published the full exchange, which shows many WikiLeaks messages went unanswered. He said the communications had been “selectively leaked”.