Trump erupts over explosive Michael Cohen testimony calling president a 'racist conman'

Donald Trump has responded angrily to reports his former lawyer will testify that he is a racist conman, claiming Michael Cohen's allegations are an attempt to reduce his prison time.

The president's former attorney is expected to tell the House oversight committee on Wednesday he is a "racist, a conman and a cheat" and that he was negotiating a business deal in Russia on his client's behalf during the 2016 presidential election.

But in his first public response to the revelations, Mr Trump said on Twitter: "Michael Cohen was one of many lawyers who represented me (unfortunately).

"He had other clients also. He was just disbarred by the State Supreme Court for lying & fraud. He did bad things unrelated to Trump. He is lying in order to reduce his prison time. Using Crooked’s lawyer!"

Mr Trump's claim Cohen was merely "one of many lawyers" - an apparent attempt to distance himself from the 52-year-old - is in stark contrast to a 2012 tweet in which he described Mr Cohen as his EVP (executive vice president).

Despite Mr Trump's attempts to discredit his former lawyer's truthfulness, Cohen is set to provide "irrefutable" evidence to back up his claims about the president.

Those allegations, made under threat of perjury, include that Mr Trump was aware of communications between his presidential campaign and WikiLeaks, and that he was lying to the American people when he insisted he has no business in Russia.

“In conversations we had during the campaign, at the same time I was actively negotiating in Russia for him, he would look me in the eye and tell me there’s no business in Russia and then go out and lie to the American people by saying the same thing,” Cohen will say. “In his way, he was telling me to lie.”

Cohen will also claim Mr Trump directed him to send letters to the president's former schools threatening them with legal action in order to prevent the release of his exam scores.

It came on the same day Mr Trump is meeting North Korean leader Kim Jong-un at a summit in Vietnam intended to address the communist state's nuclear weapons ambitions.

"All false reporting (guessing) on my intentions with respect to North Korea. Kim Jong Un and I will try very hard to work something out on Denuclearization & then making North Korea an Economic Powerhouse," Mr Trump tweeted on Wednesday afternoon in Vietnam.

"I believe that China, Russia, Japan & South Korea will be very helpful!"