Anderson Cooper shocked his viewers after he told fellow commentator Jeffrey Lord that he'd 'defend Trump if he took a dump on his desk!'

The frustrated CNN host was discussing Trump's recent 'nut job' comments about his recently fired FBI director James Comey.

'You can't defend what the president of the United States just said,' Cooper told Lord during the live show on Friday.

Anderson Cooper (left) shocked his viewers after he told fellow commentator Jeffrey Lord (right) that he'd 'defend Trump if he took a dump on his desk!'

But when the conservative commentator tried to do just that, Cooper snapped: 'If (Trump) took a dump on his desk, you would defend it.'

Lord looked stunned before bursting out laughing at the extraordinary comment.

'I mean, I don't know what he would do that you would not defend,' Cooper back-paddled. 'I mean, you're a loyal guy, I think that speaks well of you.'

Cooper later apologized on Twitter for his comment saying: 'I regret the crude sentence i spoke earlier tonight and followed it up by apologizing on air.

'It was unprofessional. I am genuinely sorry,' he wrote.

The frustrated CNN host was discussing Trump's recent 'nut job' comments about his recently fired FBI director James Comey when he told Lord: 'You can't defend what the president of the United States just said,'

But when the conservative commentator tried to do just that, Cooper snapped: 'If (Trump) took a dump on his desk, you would defend it'

Lord looked stunned before bursting out laughing at the extraordinary comment

Cooper later apologized on Twitter for his comment calling it 'unprofessional'

The comment has divided opinion online, with many praising Cooper's straight talking.

'No apology needed,' one Twitter user wrote. 'Thank you for saying what the rest of us were thinking. Lord is an intellectually bankrupt embarrassment to CNN.'

But others have slammed the CNN host for his 'lewd' language, saying he has 'cracked'.

It is not the first time Cooper has lost his patience on air.

His interview with White House counselor Kellyanne Conway recently went viral, after he made an incredible eye roll at one of her comments.

In the most recent discussion with Lord, they were discussing the meeting notes that White House aides circulated internally, which stated that President Donald Trump met with Russia's ambassador and foreign minister just one day after Comey was fired and told them the ousted FBI director was 'a real nut job' whose departure would make life easier for him.

'I just fired the head of the F.B.I. He was crazy, a real nut job,' Trump said, according to the summary. 'I faced great pressure because of Russia. That's taken off.'

Trump also assured the Russian envoys: 'I'm not under investigation.'