Trump after pardoning Arpaio gives plug for another polarizing sheriff

— -- President Donald Trump on Twitter plugged a book by controversial Sheriff David Clarke in Milwaukee, Wisconsin, calling it "a great book by a great guy."

The president's promotion of Clarke's book comes a little more than a day after he pardoned Sheriff Joe Arpaio in Arizona, who had been convicted of contempt for violating a federal court order to stop detaining people solely based on their immigration status.

Like Arpaio, Clarke is a polarizing figure. Both endorsed Trump in the presidential campaign and spoke at the Republican National Convention.

Milwaukee County Sheriff Clarke is a conservative firebrand known for his cowboy hat. He has called himself "one of those bare-knuckles fighters" and has been critical of what he has called the "hateful ideology" of the Black Lives Matters movement.

Two weeks ago, after violence in Charlottesville, Virginia, following a white nationalist gathering, Clarke was quick to praise Trump because he "didn't take sides"

A few days ago, as a threatening hurricane neared the Texas coast, Clarke tweeted that "Democrats and lib media are no doubt hoping for Hurricane Harvey to make a direct hit on Texas so they can blame @realDonaldTrump."

Clarke's jail has come under scrutiny, with four people having died while in custody there in 2016, according to the Milwaukee Journal-Sentinel. One of them died from dehydration after having gone with out water for seven days. An inquest jury earlier this year recommended charges in that death against seven staff at the jail, not Clarke. The District Attorney is continuing to weigh that recommendation, the Journal-Sentine lreported.

ABC News' Chris Donovan contributed to this report.