Story highlights Clarke is a loyal supporter of President Donald Trump

He is known for his incendiary conservative commentary

(CNN) Milwaukee County Sheriff David Clarke -- a loyal supporter of President Donald Trump who is reviled by civil rights advocates -- resigned from his post Thursday, according to County Clerk George Christenson.

Known for his often jaw-dropping rhetoric and incendiary conservative commentary, Clarke had served as one of the country's more well-known sheriffs since 2002, but he raised his national profile as a regular surrogate for the Trump campaign.

Clarke did not provide any reasons for his departure in a resignation letter obtained by CNN and did not respond to requests for comment.

In Nashville for National Fraternal Order of Police convention. They endorsed @realDonaldTrump for POTUS.👍

With one of Nashville's finest. pic.twitter.com/7EhMupFrcm — David A. Clarke, Jr. (@SheriffClarke) August 31, 2017

Thursday afternoon Clarke posted a picture of himself on Twitter "(i)n Nashville for National Fraternal Order of Police convention," leaving no hint of his imminent resignation.

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