Angela Rayner took a brutal swipe at Rishi Sunak in her Labour Party Conference speech, describing him as "just Ken".
She accused the Prime Minister of "living in [Liz Truss]'s world".
Addressing the main stage, Rayner accused Sunak of "breaking Britain", saying the Conservative Party is "not fit to govern".
The Labour Party's Deputy Leader said Sunak's party has "dragged the UK down".
She said: "At conference, Liz Truss was back. And one thing did become clear - we all know that he's just Ken living in her Barbie world.
"And what a contrast we are to the Tories, with Keir at the helm, Labour shadow cabinet is hungry for change".
Addressing the party's conference in Liverpool, she added: "They're holding us back. And this is why Labour's first and most important mission in Government is to grow the economy."
She said Sunak "simply can't stand up for the country in front of his party".
Rayner heralded the party's victory in Rutherglen, a by-election which saw the SNP ousted by Labour.
She said the Labour Party did not elect her to be Deputy Leader of the Opposition, instead saying: "You elected me to be Deputy Prime Minister of a Labour Government".
She said Labour is "already delivering in power", adding: "Our movement has never been so unified, so focused around one aim - to give Britain its future back".
Ahead of her speech, the stage was taken over by a protester who appeared to be wearing a Palestine Solidarity Campaign lanyard.
The protester attempted to address delegates in the main hall but had his microphone cut off.
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The protester attempted to address delegates in the main hall but had his microphone cut off
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He was then removed from the hall by security.
The intervention came just moments before Rayner addressed the main stage, opening the conference.
