Former Mayor Rudy Giuliani has resigned from his powerhouse New York law firm.

Giuliani took a temporary leave of absence from the firm Greenberg Traurig when he joined President Donald Trump's legal team last month. But in a statement Thursday, the former mayor says he intends to permanently resign from the firm.

"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," he said.