Marc Kasowitz, who has been Trump's go-to lawyer for years on both personal and business matters, is defending a Russian bank, OJSC Sberbank, in an ongoing lawsuit in US court. He also represents a company controlled by a Russian billionaire, Oleg Deripaska, who has close ties to the Kremlin.
Kasowitz' clients with Russian ties may not pose any legal conflicts of interests as he prepares to help Trump navigate an investigation that the president calls "a witch hunt." But the optics of the situation -- a lawyer with Russian-linked clients representing a president, whose campaign is being investigated for alleged collusion with Russia -- could make a messy situation for Trump even messier.
Larry Noble, general counsel for the non-partisan Campaign Legal Center, said Kasowitz' client list could potentially raise questions for the White House.
"Could there be some line of communication between these clients and the White House? Is there any situation where the interests of one conflicts with the other? These are the questions that come up," Noble said in an interview.
Josh Galper, a crisis management attorney and co-founder of the firm Trident DMG, said if Kasowitz is hired, as expected, his clients with Russian ties could become another unnecessary distraction for the White House.
"The first rule of crisis management is not to create another crisis for yourself through the people that are representing you," Galper said. "When you're in an environment like the White House, you have to apply judgment to problems of appearance."
Trump's expected decision to hire Kasowitz comes the week after the Justice Department appointed a special counsel to oversee the federal investigation into Russian interference in the 2016 election. Congressional committees are also investigating Russia's role.
Court documents show Kasowitz represents OJSC Sberbank, one of the country's largest banks.
A 2016 lawsuit accuses OJSC Sberbank of conspiring with granite-mining company executives in an "illegal scheme to... dismantle" a competitor and seize its assets. An attorney for some of the other defendants told CNN the allegations are unfounded.
Other defendants in the case include former Russian officials, such as the former minister of economy and trade, though Kasowitz is only listed as representing the bank in the case. The case is still pending.
Kasowitz is also listed in a federal lawsuit as an attorney for Veleron Holding BV, an investment company controlled by Deripaska.
Deripaska has served as a representative of Russia on the Asia-Pacific Economic Cooperation Business Advisory Council and was photographed with Putin at one of the council's meetings in 2006.
Kasowitz serves as an attorney for Veleron in a federal lawsuit under appeal involving Morgan Stanley.
In 2012, Veleron accused Morgan Stanley of insider trading on a deal that involved a separate bank financing Veleron's investment in a Canadian auto parts manufacturer.
In 2015, a jury ruled for Morgan Stanley, but Veleron has appealed the case -- with Kasowitz listed as an attorney.
The White House did not respond to a request for comment on Kasowitz' Russian clients.
Kasowitz could not be reached for comment on his representation of OJSC Sberbank of Russia. A spokesperson for his firm previously told CNN that Kasowitz only represents the Veleron firm, and not Deripaska personally. .
"Our representation of Veleron did not emanate from and has nothing to do with our representation of any Trump personnel or entities, and we have never relayed information or facilitated communication between Mr. Deripaska and his representatives and President Trump and his representatives," the spokesperson said in the prior statement to CNN.
Deripaska, who owns the Russian industrial group Basic Element, also has connections to Trump's former campaign chairman Paul Manafort, who worked for Derispaka as a consultant.
In 2008, Deripaska invested about $19 million in a business venture launched by Manafort and other partners. The partnership invested in a Ukrainian telecommunications company - Black Sea Cable- but the deal failed.
Deripaska's subsequent legal claims against Manafort's business venture appear to have been dropped.
"Mr. Manafort believes the matter is dormant and will not be pursued further," a spokesperson for Manafort previously told CNN.
In a statement published in US newspapers in March, Deripaska said he would take part in any related hearings before Congress.
Putin, asked about the possibility of Deripaska testifying at a US congressional hearing, said he was not against it.
"That's his right. Let him do it," Putin said in March during a panel in the Russian city of Archangel.
Kasowitz has defended Trump in many legal matters over the years. He represented him in the suit filed by the New York Attorney General against Trump University and in a 2006 case filed against a journalist who wrote a book about Trump.
Kasowitz also sent letters on behalf of Trump threatening legal action during his presidential campaign. An October 2016 letter signed by Kasowitz demanded that the New York Times retract a story about two women who said that Trump had touched them inappropriately.