Republican Convention 2016 Cleveland
Milwaukee County Sheriff David Clarke salutes the crowd prior to delivering a speech on the first day of the Republican National Convention Joe Raedle/Getty

A Trump-supporting sheriff is facing criticism after he suggested it was time to stop complaining and "bring out the pitchforks and torches" in response to corrupt government and media.

Milwaukee county sheriff David A. Clarke Jr. has long been a vocal supporter of Donald Trump and frequently posts pro-crump messages on social media.

He wrote on Twitter: "It's incredible that our institutions of gov, WH, Congress, DOJ, and big media are corrupt & all we do is bitch. Pitchforks and torches time."

The sheriff had accompanied his words with a generic picture of a group of people holding touches and pitchforks, and immediately drew criticism from others on social media with his post.

One user, Mikel Jollett, wrote: "As a metaphor, torches and pitchforks refer to mob violence. This is literally a call to violence", while another, Cowboy G, added: "David, is treason still a crime in the US? Please arrest yourself. PS. You have no political future."

The sheriff, who spoke at the Republican National Convention, has also previously defended Trump over lewd comments he was caught on tape expressing in 2005, stating: "This isn't about a salacious audio tape. It's about Dems trying to hold onto power. Why can't sanctimonious GOP pols ever figure that out?"

He also spoke out against media reporting of his tweets, suggesting more time should be spent on reporting Wikileaks' release of emails from Hillary Clinton's campaign.