Sam Clovis, a former Trump campaign official who has become entangled in special counsel Robert Mueller's Russia investigation, has withdrawn his nomination for a top post in the Agriculture Department.

“We respect Mr. Clovis’s decision to withdraw his nomination," White House press secretary Sarah Huckabee Sanders said in a statement.

Clovis was nominated to be the Agriculture Department's chief scientist. He was already facing scrutiny over his apparent lack of credentials for the post.