New York: When asked which aspects of Donald Trump's presidency they would like to change, Trump's most ardent supporters usually respond with the same answer: they wish he'd lay off the tweeting.

Michael Cohen, President Donald Trump's former attorney. Credit:AP

From threatening North Korean leader Kim Jong-un to accusing a prominent TV host of having a facelift, Trump uses social media in an unfiltered, impulsive way that no other president has before - or likely will ever again.

Even those who have grown numb to Trump's social media musings were stunned on Monday morning by a string of tweets that legal experts said crossed the Rubicon from outlandish to illegal.

Among those accusing Trump of "witness tampering" via Twitter - a crime punishable by up to 20 years in prison - was George Conway, a prominent Republican lawyer and the husband of top Trump adviser Kellyanne Conway.