Michael Cohen, Donald Trump`s longtime lawyer and fixer, assailed his former former boss as a "racist" and a "conman" in explosive testimony before the US Congress Wednesday. Addressing the House Oversight and Reform Committee, Cohen -- who has been sentenced to jail for crimes related in part to his work for Trump -- expressed regret for his past loyalty. "I am ashamed that I chose to take part in concealing Mr. Trump`s illicit acts rather than listening to my own conscience," Cohen said. "He is a racist. He is a conman. He is a cheat." Cohen said he was presenting "irrefutable" evidence of Trump`s wrongdoing including a check reimbursing "hush money" paid to two women shortly before the 2016 election. He also said Trump directed negotiations for a Trump Tower in Moscow through the 2016 election campaign even while denying any business ties with the Russians.