Washington DC - Donald Trump's former national security adviser John Bolton had some harsh words regarding his old boss' recent cabinet picks for his upcoming presidential administration.

On Thursday, Bolton – who served in Trump's first administration – heavily criticized the president-elect for choosing Florida Rep. Matt Gaetz to be Attorney General and called on the Republican Party to oppose his nomination.

"Gaetz must be the worst nomination for a cabinet position in American history," Bolton wrote in an X post.

"This is something that falls well outside the proper scope of deference to a president nominating members of his senior team," he continued.

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"Gaetz is not only totally incompetent for this job, he doesn't have character or the civic virtue the Founding Fathers wanted."

Bolton reiterated his argument in an interview with NBC News, but admitted an opposition vote may never pass because lawmakers will be "intimidated" by Trump, as it is "the way he governs."

In another interview with NewsNation, Bolton took aim at Trump appointing former Hawaii Rep. Tulsi Gabbard to be Director of National Intelligence, which he says is "sending a signal that we have lost our mind when it comes to collecting intelligence" because she is "a serious threat to our national security."

"I don't think either she or Matt Gaetz ought to have a confirmation hearing until they have both had full-field FBI investigations," he added. "And then I think the Chinese would say, 'Maybe they are serious.'"

Gaetz has been representing Florida's 1st District since 2017 and has established himself in the US House of Representatives as a staunch supporter of Trump.

Prior to Trump's appointment, Gaetz was under investigation by the House Ethics Committee regarding multiple criminal allegations against him, including sex trafficking of a minor, which carried a minimum sentence of 10 years in prison.

Despite the bad publicity surrounding the investigation, Gaetz still managed to win re-election to his seat.

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Quickly after Trump's appointment, Gaetz resigned from his House seat, effectively putting an end to the committee's investigation.

Critics are calling for the ethics committee to release a report on their finding ahead of Gaetz being officially confirmed into his position.