The hearing begins with Republican Chairman Mark Meadows complaining about some late breaking evidence entered into the record.

"If this was just an oversight, Mr chairman, I could look beyond it," he said.

"But it was an effort by this witness and his advisers to show his disdain for this body," said Meadows, his voice rising as he spoke.

Meadows' motion to dismiss or delay the hearing failed after a voice vote by all 42 committee members.

Image source, Getty Images

Large posters with quotes from the Southern District of New York where Cohen pleaded guilty to eight crimes - including campaign finance violations, tax fraud, bank fraud, and lying to Congress - have appeared in the committee room.

"Cohen pled guilty to a veritable smorgasbord of fraudulent conduct... Each of the crimes involved deception and each appears to have been motivated by personal greed and ambition."

Another poster says Cohen had been expecting a White House job, and sought to capitalise on his relationship with the president when no such offer was made.

It's unclear which member of Congress brought the quotes, but it seems probable that it was a Republican.

Republicans have been attacking Cohen as a "convicted liar", saying he's only lashing out against a boss that spurned him.

Paul Wood
World Affairs Correspondent

Anyone who’s met Michael Cohen recently will tell you that he’s burning with anger at having to take the blame for crimes he says were instigated by Trump.

It seems he's spent weeks being intensively prepped by his lawyers for this moment and intends to do the President fatal damage.

The White House talking points - farmed out to surrogates such as Donald Trump Jr - are that he’s a "disgraced liar" and "convicted perjurer".

Cohen certainly knows he has – as he says in his testimony – a credibility problem.

That’s why he’s attempting to wield a stiletto, not swing an axe, each charge backed up by what he calls “documents that are irrefutable” – hence the dramatic production of a cheque apparently signed by Trump (the alleged refund for paying off Stormy Daniels).

He won’t talk much about whether the Trump campaign colluded with Russia. In fact, he says he has no direct knowledge of collusion.

He will, though, say he witnessed Trump in a telephone conversation during the campaign that showed he knew in advance Wikileaks was about to publish emails hacked - by Russia - from the Democrat Party.

That would be hugely significant, if true. Trump has always denied it.

Cohen's first hearing yesterday was an eight-hour closed-door session before the Senate Intelligence Committee - the panel he admits lying to in 2017.

The ex-lawyer apologised to senators, US media say, but what else transpired during the hearing has not been publicised.

"I really appreciate the opportunity that was given to me to clear the record and to tell the truth," Cohen told reporters afterwards.

He said he was "looking forward" to Wednesday's public hearing.

"I'm going to let the American people decide exactly who is telling the truth."

We asked a former federal prosecutor and a Republican strategist for their views on how Cohen's conviction affects Donald Trump.

Image source, Reuters

The hearing will be opened by Democratic Chairman Elijah Cummings.

Ranking Republican Chairman Jim Jordan will go next, unless Cummings first hands off to another Democrat.

Jordan may motion to immediately adjourn the hearing, and will have 5-10 minutes to deliver remarks.

Cummings will then introduce Cohen and swear him in.

Cohen then has about 20 minutes to give his opening statement before every member of the committee will be given five minutes to speak.

The hearing will alternate between Democrats and Republicans until each of the 42 committee members have had their turn.

Expect serious fireworks as Cohen faces Republican cross-examination.

The hearing is expected to last four to five hours, and may include a lunch break.

The president took a brief break from preparing for his meeting with Kim Jong-un to tweet about Michael Cohen.

Image source, Reuters

Cohen has arrived at the House Oversight Committee hearing room in the Rayburn House Office Building on Capitol Hill. It's his second of three consecutive days of congressional testimony, though yesterday's appearance before a Senate committee was behind closed doors. Today's is before the full glare of the media.

Image source, Reuters

Today should have been the day that Donald Trump strode the world stage as a would-be peacemaker in Hanoi, Vietnam.

But while he holds a nuclear summit with the North Korean leader, the US president's former right hand man is pouring a bucket of political manure over his image.

During public testimony to a congressional committee, Michael Cohen is about to level explosive allegations against the president of deceit and racism.

Prepared testimony by Cohen - who once boasted he would take a bullet for the president - has been published ahead of the main event.

Here are some of the key points he's expected to make:

• Cohen will claim Trump knew beforehand about hacked Democratic emails, and that he was in the room when political adviser Roger Stone told Trump he'd been speaking to Wikileaks' Julian Assange about the leak
• He'll say Trump inquired about plans for a tower in Moscow despite telling the public he had no business dealings in Russia - in part because "he never expected to win the election [and] stood to make hundreds of millions of dollars" from the project
• Cohen will claim Trump made racist comments about former President Barack Obama and once told Cohen - "black people would never vote for him because they were too stupid"

What else might Cohen say? Read our full story here.