With the Russia probe gathering steam, President Donald Trump’s legal team underwent a major shake-up, with the president’s longtime personal attorney Marc Kasowitz resigning Thursday, multiple reports claimed.

Kasowitz, the president’s lawyer since the past 15 years and the lead lawyer in Special Counsel Robert Mueller’s investigation into Russia's meddling in last year's presidential election, would take a diminished role, a CNN report stated.

Attorney John Dowd, along with Jay Sekulow, will now be the president's primary personal attorneys for the investigation, CNN reported, citing two sources with knowledge of the situation.

Read: Trump Lawyer Marc Kasowitz Threatens Stranger In Email: 'Watch Your Back Bitch'

However, CBS News took to Twitter to announce Kasowitz was no longer a part of the president’s legal team.

Kasowitz recently made headlines for threatening a public relations professional, who had asked him to resign from Trump's legal team.

According to ProPublica, one of Kasowitz’s emails read: “And you don't know me, but I will know you. How dare you send me an email like that? I'm on you now. You are f------ with me now. Let’s see who you are. Watch your back, b----."

In another email, he wrote: “I already know where you live, I’m on you. You might as well call me. You will see me. I promise Bro.”

He later apologized for the emails.

Besides Kasowitz, Mark Corallo, spokesman and communications strategist for Trump's legal team, too announced his resignation.

Although the reason behind his exit is unclear, Politico, citing an unnamed source, reported Corallo complained “too much fighting all the time” in the White House and that there was a constant conflict between the lawyers.

Meanwhile, USA Today reported that Trump has tapped a highly experienced corruption and white-collar crime lawyer Ty Cobb to be a part of his team.

CNN reported attorney Cobb will take the lead from inside the White House on the probe when he formally starts his job July 31.

“He brings to the White House a lot of experience the president has not had,’’ Dowd said, USA Today reported.

Read: Trump Lawyer Broke Ethics Rules By Telling White House Staff Not To Hire Attorneys, Complaint Claims

Prior to his new role, Cobb worked with the Washington, D.C., law firm Hogan Lovells. His bio on the company’s website said: “Ty Cobb, a long-time leader at Hogan Lovells, has been widely recognized as one of the premier white collar, Securities and Exchange Commission (SEC) enforcement, and congressional investigations lawyers in the world. Clients managing crises, allegations of corruption, and other critical matters turn to Ty to guide them.”