The Labour leader was accused by Tories of being “jealous” of his deputy after launching into the rant. He was accused by one Tory attempting to prove he was “one of the lads” in a desperate bid to connect with voters across the country.
“I think he is jealous because she’s got a bit more spark about her,” the MP told Express.co.uk.
“She is an authentic human being, whereas Starmer isn’t and never will be.
“Starmer is so buttoned up, it’s hard to believe.
“He is a very wooden, robotic politician. He is a lawyer posing as a politician.”
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They added: “Kier Starmer will be lucky if he even connects with the people of his constituency, Holborn and St Pancras.
“He is an archetypical, metropolitan lawyer and he is clearly significantly jealous.”
Speaking on a politics podcast, the Labour leader called Mr Johnson a “complete bullsh*tter” who “took the p*ss” out of the public over the so-called Partygate saga.
He told The Rest Is Politics podcast: “I think that he is a complete bullsh*tter.
“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 p*ss out of the public with his ridiculous defences afterwards.
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Ms Rayner is well known for her outspoken comments.
Last autumn she sparked anger after launching into a late night, alcohol-infused tirade against “Tory scum”.
She later apologised for her rant saying she had reflected on “our political debate” and the “abuse that now seems to feature all too often”.
Responding to Sir Keir’s remarks, the Prime Minister’s press secretary said she would “not respond with similar language”.
She added: “But I would disagree with that characterisation.
“I think Prime Minister has delivered a huge amount that was promised to the British public, not least getting Brexit done, which was delivering on the will of millions of people.
“And it’s possibly slightly hypocritical of the Leader of the Opposition to say such things when he voted against doing that 48 times”.
Labour denied that Sir Keir’s use of colourful language to describe the PM degraded the public debate.