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(CNN) —  

Rudy Giuliani has resigned from his law firm, Greenberg Traurig, in order to concentrate on his legal work for President Donald Trump during the special counsel investigation into Russian meddling in the 2016 election.

“In light of the pressing demands of the Mueller investigation, I believe it is in everyone’s best interest that I make it a permanent resignation. This way, my sole concentration can be on this critically important matter for our country,” Giuliani said in a statement Thursday.

Richard Rosenbaum, the firm’s executive chairman, said that Giuliani initially planned to play a “limited role, for a short period of time” on Trump’s legal team but that the work has turned out to be “all consuming and is lasting longer than initially anticipated.”

The former New York City mayor joined the President’s legal team last month, saying at the time he intended to work on bringing the special counsel investigation to a conclusion. Trump has repeatedly denounced the inquiry as a “witch hunt” and said there was no collusion between his campaign and Russia.

Since joining the legal team, however, Giuliani has repeatedly made headlines for wading into allegations involving the President and adult film actress Stormy Daniels, who alleges she had a consensual sexual encounter with Trump more than a decade ago. The White House has said Trump denies the affair.

Giuliani stunned political observers when he revealed Trump reimbursed his longtime personal lawyer for a $130,000 hush money payment to Daniels after the President had previously denied knowledge of the transaction. Giuliani has since insisted repeatedly the payment did not violate campaign finance laws.