President-elect Donald Trump has met with a potential chief of Homeland Security who has advocated suspending the right to a trial and sending “a million” suspected terrorism supporters to Guantanamo Bay.

Milwaukee County Sheriff David Clarke Jr. is known for his brash, outspoken tone and hard line conservative views. He met with the President-elect on Monday at Trump Tower in New York and has been tipped as a possible head of the Department of Homeland Security.

Unlike his current job at the low crime Milwaukee County, where Mr Clarke is in charge of 618 people, the Department of Homeland Security has 240,000 employees. The organisation has a wide remit, encompassing many key organisations, including the Secret Service, Coast Guard and Transport Security Administration.

In December 2015, Mr Clarke suggested suspending the right to a trial under the invocation of Article 1, Section 9 of the Constitution, which allows for the suspension of habeas corpus in the event of rebellion or invasion.

"We have no idea how many people out there have pledged allegiance or are supporting Isis, giving aid and comfort, but I would suggest hundreds of thousands, I would suggest maybe a million. It's just a guess," Mr Clarke said during a radio show he presents.

"And then you take the known terrorists that are here, and you think we're going to arrest all these people and put them in jails and then sentence them to prison? It's idiotic. [Send them to] Gitmo and hold them indefinitely under a suspension of habeas corpus. We're at war. This is a time of war. Bold and aggressive action is needed."

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Mr Clarke has said he would serve in the Trump administration if asked by the President-elect. After the meeting on Monday, a spokesperson for the sheriff declined to comment on the meeting, but a Facebook post criticising the local media later appeared on the Milwaukee County Sheriff Facebook page.

The Milwaukee Journal Sentinel has long followed the hard line sheriff, who identifies politically as a conservative but ran for his position as a Democrat, according to the newspaper’s reports of comments made in Mr Clarke’s book, Cop Under Fire.

In the book, he also wrote that suspected terrorists in the US should be treated as “enemy combatants” and should be processed by a military tribunal, rather than a civilian court.

Mr Clarke’s fitness for the job of Department of Homeland Security chief has been questioned by advocacy groups.

"This guy, who spends more time chasing media appearances than doing his job, has no business anywhere close to a job with responsibility for protecting national security," said Scot Ross, of liberal advocacy group One Wisconsin Now to the Sentinel.