Clarke’s resignation, which comes more than a year before his fourth term as sheriff is scheduled to expire, took effect at midnight, Milwaukee County Clerk George L. Christenson told The Washington Post.

It remains unclear why the sheriff, 61, left his job, a move he’s characterized as his retirement. Clarke had served as sheriff since 2002.

A longtime adviser, Craig Peterson, said Clarke is unlikely to make any public comments until next week, although the former sheriff took to social media on Friday morning to change his Twitter bio — “Sheriff (ret).,” it now begins — and to acknowledge his decision.

Clarke — described by the Milwaukee Journal Sentinel as a “controversial, Stetson-wearing official who rose to national prominence with his no-holds-barred conservative rhetoric” — quickly followed his retirement tweet with two others that touched on one of his favorite topics: the media’s treatment of President Trump.

“As Hurricane Irma approaches the Caribbean, lib media no doubt scheming on how they can weaponize this storm to use against @realDonaldTrump,” he wrote in one.

“With the fake news media’s derangement over every single move made by @realDonaldTrump,” Clarke wrote in another, “he is living rent free in their empty heads. #MAGA.”

 Asked whether the lifelong Milwaukee resident is considering a potential geographic relocation, Peterson, the adviser, would say only: “Anything’s a potential.”

Politico reported Thursday that Clarke is expected to take a job with the Trump administration. But according to a person close to Clarke, he is likely to join an outside group that supports the president’s agenda. A second person familiar with the matter said that Clarke was not expected to join the Trump administration. Both individuals spoke on the condition of anonymity to discuss private conversations.

In June, Clarke withdrew his name from consideration for an assistant secretary position at the Department of Homeland Security.

At the time, Peterson said, “Sheriff Clarke is 100 percent committed to the success of President Trump and believes his skills could be better utilized to promote the president’s agenda in a more aggressive role.”

Christenson, the county clerk, declined to comment on the contents of Clark’s resignation letter or any rationale the sheriff provided for his decision to leave the post. The resignation came with no advance notice, Christenson said, adding that he will next alert Wisconsin Gov. Scott Walker (R), who will decide on the appointment of a replacement.

The Journal Sentinel published a copy of the letter, which read:

Re: Resignation

Dear Mr. Christenson:

Pursuant to Wis. Stat § 17.01, this communication is submitted as the notice of my resignation as Sheriff of Milwaukee County commencing August 31, 2017, at 11:59 p.m.

Sincerely,

David A. Clarke Jr., Sheriff

Milwaukee County

A Democrat whose rhetoric and conservative political base more closely align with the Republican Party, Clarke has in recent years become a regular commentator on Fox News and used the platform to criticize President Barack Obama and assail many of his policies.

Clarke has compared the Black Lives Matter protest movement, which aims to counter anti-black racism, to the Ku Klux Klan, suggesting it would team with the Islamic State to overthrow the federal government. He labeled anti-Trump demonstrators as “anarchists,” and said African Americans sell drugs “because they’re uneducated, they’re lazy, and they’re morally bankrupt.”

His 15-year tenure as sheriff has also been a source of controversy.

At least four people died in the Milwaukee County Jail between April 2015 and November 2016, including a newborn baby whose birth occurred unknown to Clarke’s staff. In another case, his staff was accused of withholding water from an inmate, who eventually died, for one week. In January, a jury awarded $6.7 million to a woman who said she was repeatedly raped by guards at the jail.

He and his staff are the subject of numerous other lawsuits alleging abuse and mistreatment.

While Clarke was under consideration for the Homeland Security job, reports surfaced that he had plagiarized large portions of his master’s thesis. He disputed those claims and called the CNN reporter who broke the story “a sleaze bag.”

The sheriff emerged as one of Trump’s most visible and enthusiastic supporters during last year’s campaign, delivering a much-discussed address at the Republican National Convention.

Addressing the Republican crowd in Cleveland he declared, “Blue lives matter in America,” a pointed response to growing criticism, throughout the nation, about law enforcement’s use of deadly force, and Clarke made clear his feeling that the threats facing his officers and others have become only more extreme. In the convention speech, he praised a Baltimore court’s decision to acquit one officer implicated in the death of a man, Freddie Gray, who suffered severe spinal injuries while in police custody.

Clarke was discussed as a potential Homeland Security secretary early in the Trump administration’s transition, but those close to the president-elect worried that various scandals and a host of controversial statements would impede the sheriff’s ability to win Senate confirmation.

On Thursday, Clarke attended the Fraternal Order of Police national convention in Nashville, posing for photos alongside admirers and reminding his 768,000 Twitter followers that the organization backed Trump during last year’s election.