Dame Louise Casey tore apart Rishi Sunak in a brutal takedown in which she accused the PM of "selling nonsense".
The former government adviser said the Prime Minister was pushing out "dangerous" spin and was claiming things were fact when they weren't. Baroness Casey said she felt "sad" after watching the BBC's Laura Kuenssberg interview Mr Sunak as he failed to grasp the state the country is in.
"We're in just the most extraordinary place in our country. I've just done this series called Fixing Britain on Radio Four, and we need to fix Britain," she said. "I didn't take from that [interview] any sense that there's an acceptance that things are as bad for people as they are. Things are really bad for an awful lot of people out there."
During the interview, the PM said tax cuts funded by cutting benefits would be about creating "fairness", as he said Britain's welfare system "is not working". He also said he had full confidence in the Rwanda scheme despite a leaked report this weekend suggesting that he was not convinced of the plan's effectiveness while serving as Chancellor under ex-PM Boris Johnson.
Baroness Casey said: "Spin is such a dangerous thing. To say: those are the facts when they're not the facts. They're really not the facts you know, from the boats, which is just a headline rather than... an immigration policy to the latest let's crack down on welfare. Well, they always crack down on welfare. If they were going to crack down on welfare, why haven't they done it by now?"
Rishi Sunak must be a leader, not just a managerShe added that Mr Sunak was "probably quite a decent bloke" but was in this "invidious position" when running into a general election. She added: "He is selling nonsense. I mean, it just rang hollow. One thing after the other. And I can't help - I can hear it in my tone - feel a cross between angry and upset."
Mr Sunak also said in his interview that the Government had reached a pay resolution with every other part of the NHS, except for junior doctors. But unions criticised said he is "incorrect" for claiming he has settled pay disputes with nurses, consultants and speciality doctors. Junior doctors in England are in the middle of a six-day strike, which is the longest walkout in the history of the health service.
Speaking about junior doctors, Baroness Casey added: "People need to know that people who have trained for seven years and hold our lives in the hands - these aren't trainees, these aren't medical students - we're paying them £15 an hour. I mean, it all rings hollow and what I wanted was some acceptance, that actually Britain is pretty - we're pretty low, actually."
She went on: "And a lot of people in Britain will not feel these tax cuts. And the idea that all of these people have benefit scroungers when most of them are working - the vast majority of people on benefit are working. So, yeah, I'm not the happiest person to start the programme."