Keir Starmer has described Boris Johnson as ''a complete bull sh*tter'' who ''took the p*ss out of the public''.
In a ferocious attack on the departing Prime Minister, Mr Starmer said his legacy was to ''debase politics and drag everybody into the gutter''.
He also labelled the Tories in the Conservative leadership race as ''B-grade candidates'' - and said he would take any of them on.
The Labour leader made the comments on 'The Rest is Politics' podcast, hosted by Alastair Campbell and Rory Stewart.
He said: ''I think that he is a complete bullshitter. And I think he's been found out and I'm really struck with the Partygate stuff because it wasn't just that he did things which broke the rules.
''It's that he then took the piss out of the public with his ridiculous defences afterwards.
''And in the local elections, I accept that not everyone on doors was saying 'it's that that's done it for me', but there was a general realisation that this guy bullshits, and if he's bullshitting about that, he's probably bullshitting about everything.
''All this stuff about levelling up - when people can see there's not much happening around near then - I think this, there's this sense that this guy doesn't mean a word that he says, and that goes very, very deep... I mean that's why I don’t think there was ever any way back for him from that.
"And I think it's really good for the country that we're seeing the back of him.''
Taking about Tory contenders, Mr Starmer said: ''I think they're all B-grade candidates, I really don't mind which of them I go up against…most of them are tainted by having propped up Johnson.
'It's no good now Rishi Sunak saying now, 'I'm the guy with principles, I'm the guy with integrity'. He propped him up for three years. Truss the same.
''I constantly get this question - which of them do you fear? I don't fear any of them.
''They're a busted flush, the whole project is broken. I think the Tories have been more divided for longer than people think.''
He added: 'I think one of the biggest issues and challenges in politics now is that because of people like Johnson who debase politics and drag everybody into the gutter, there is this general sense that you're all the same.
''And that is the most corrosive thing. Because once people think you're all the same, they lose heart in the idea that politics is a force for good.
''And that is a very dangerous place to get to. It's why Johnson in the end drags everyone into the gutter with him. He wants everyone down in that place with him.''
On Brexit, he said: ''There are things that can be done to make Brexit work and we've got to look ahead to it.
''I honestly think that just sort of tearing ourselves apart for another five years would be the worst of all options for an incoming Labour government.”
The podcast is part of the Acast Creator Network.
