Carl Icahn announced Friday that he is stepping down from his role as special advisor to President Donald Trump on regulation.

In a letter to the president posted to Icahn's website, the billionaire investor said the decision came after a Friday conversation between the two men. Icahn wrote that he made the decision with the president's blessing.

The famed investor said he resigned from the role to avoid "partisan bickering" about his position. Icahn said he did not want that scrutiny to affect the Trump administration's work on regulatory reform.

The billionaire had been a frequent critic of Obama-era rules. He previously said the EPA was one of the worst-run agencies he had ever seen.

Icahn also took the opportunity to again insist that he "never had a formal position with your administration nor a policymaking role." He reiterated that his advisory position did not give him access to nonpublic information.

Those statements referenced skepticism from Democratic lawmakers regarding Icahn's informal advisory role. Some Democrats had asked regulators to look into whether Icahn, a major fossil fuel investor, had engaged in any improper market behavior.

Read Icahn's full letter to Trump below: