Donald Trump has appointed lawyer Marc Kasowitz to represent him in an inquiry into Russia's alleged meddling in the US presidential election and any links to the Trump campaign, US media report.
Mr Trump has used services of the New York lawyer - known as a tenacious litigator - for more than a decade.
Last week, former FBI boss Robert Mueller was named special counsel for the Department of Justice inquiry.
President Trump denies any collusion between his campaign and Russia.
However, US intelligence agencies believe Moscow tried to tip the 2016 election in favour of Mr Trump.
Mr Kasowitz and the White House have so far made no public comments on the reported appointment.
Mr Kasowitz is well known to Donald Trump, and it was he who - during the presidential campaign - threatened to sue the New York Times newspaper if it didn't retract a story about Mr Trump touching women inappropriately.
The Times stood by its story and a retraction was never published.
"He can be aggressive - he's got that in him for sure," John Quinn of Quinn Emanuel Urquhart and Sullivan, who has worked with and opposite Mr Kasowitz, was quoted as saying by Reuters.
"He also can be smooth as silk, respectful and deferential," Mr Quinn added.
Calls for a special investigation had mounted since President Trump fired the most recent FBI director, James Comey, earlier this month.
The FBI and Congress are also looking into potential links between Mr Trump's campaign team and Russia.