Cohen: Trump may not go peacefully if he loses in 2020

Donald Trump's former lawyer wrapped up hours of explosive congressional testimony on Wednesday by warning that the US president may not accept a "peaceful transition of power" if he loses re-election in 2020.

Michael Cohen, who implicated the president in federal crimes and said Trump would do anything to win, said he offered his bombshell alarm as someone who knows the president well.

"Given my experience working for Mr Trump, I fear that if he loses the election in 2020, that there will never be a peaceful transition of power," he said in a final statement to the House Oversight and Reform Committee after hours of public testimony.

Cohen acknowledged that his blind loyalty to Trump "has cost me everything," and that the former fixer will be headed to prison in May for three years, for hush money payments and lying to Congress.

"But I will not sit back and say nothing," he said as he launched his warning.

Cohen had repeatedly expressed remorse during his five-hour grilling, and painted a picture of a sprawling Trump organisation where "everybody's job (was) to protect Mr Trump."

"My loyalty to Mr Trump has cost me everything: my family's happiness, friendships, my law license, my company, my livelihood, my honour, my reputation, and soon my freedom," he said.

Cohen also had a message for Trump himself: "You take responsibility for your own dirty deeds," he said.

"You don't use your power of your bully pulpit to destroy the credibility of those who speak out against you."

On his way out, Cohen briefly addressed reporters, saying he hoped his testimony "helped in order to heal America."

Trump's re-election campaign did not specifically address Cohen's claim that the president might not peacefully give up power.

But it quickly hit out at his "deceitful" testimony.

"Michael Cohen is a felon, a disbarred lawyer, and a convicted perjurer who lied to... Congress," the campaign's national press secretary Kayleigh McEnany said.