Iain Dale laid into Diane Abbott, the possible next home secretary, over her alarming leniency on counter-terror legislation.
The LBC host pointed out the Mrs Abbott voted against listing Al-Qaeda as terrorists in 2001 – the year the extremist group struck the Twin Towers in New York.
The left-wing politician, who is a strong ally of Labour leader Jeremy Corbyn, struggled to respond when challenged about her past views on terrorism.
This morning's cringeworthy interview will add to mounting questions about Mrs Abbott's competence to take over domestic security if her party wins the election on June 9.
In the wake of the Manchester terror attack, Dale quizzed the candidate for Hackney on her disturbing voting record.
Iain Dale laid into Diane Abbott, the possible next home secretary
The LBC host repeatedly asked Mrs Abbott about whether Mr Corbyn was right to link foreign policy to terror attacks.
She said that he would be better asking Britain's security services before adding that interventions do not help Britons feel safer.
This prompted Dale to declare: "I am talking to you! I want to know what you think.
"France has experienced far more terrorist attacks than us, and they did not go to Iraq. How can this be linked to foreign policy?
In a fierce tirade, Dale continued: "Is it not the fact that these depraved men are brainwashed into believing that the Western way of life is incompatible with them, to hate our values?
"The leader of the mosque in Dilsbury, where Abedi prayed, refused to take any responsibility for not reporting him. Is that not a problem?"
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The LBC host pointed out the Mrs Abbott voted against listing Al-Qaeda as terrorists in 2001
In 2001 you voted against prescribing al-Qaeda as a terrorist group. Why?
Dale then turned to the Labour candidate's record on terror legislation, pointing out that she voted against prescribing al-Qaeda as a terrorist group in 2001.
She responded:"It was not just al-Qaeda, there was a concern that we had to be careful before making a series of groups illegal."
But, Dale hit back: "You know, al-Qaeda was a well-known terror group at the time.
"You, John McDonnell and Corbyn all voted against them being listed as a terror group. How on earth can someone who is going to be home secretary think that?
"How on earth can someone who is going to be home secretary think that?"
When Mrs Abbott dismissed these concerns, the radio host pointed out her notorious quote from 1984, where the left-wing politician said "every defeat of the British state was a victory for all of us".
The Hackney candidate struggled to respond to this before simply repeating that this was from 34 years ago and insisted she had moved on.
The Hackney candidate struggled to respond to Dale's questions
In the wake of the Manchester terror attack, Dale quizzed the candidate for Hackney on terror
Twitter lit up as users condemned Mrs Abbott's weak stance on terrorism.
Others delighted in her "embarrassing" performance as Dale took her to task.
One user tweeted: "I wouldn’t trust Diane Abbott to run a bath, let alone the Home Office. Same goes for Corbyn & McDonnell."
Another summed up the mood: "Oh dear – another car crash interview for Diane Abbott. When will she learn?"
Some tweeted that the Labour candidate was "not fit to serve" over domestic security.