The shadow foreign secretary appeared to lose her cool as she was grilled about the party’s floundering poll ratings since the hard-left MP took the helm in 2015.
Unite Union boss Len McCluskey, who helps fund the party, has now said Mr Corbyn should be allowed “15 months” to turn the party’s fortunes around.
Emily Thornberry appeared to snap during a heated debate with Channel 4's Jon Snow
Ok, do you want me to speak?
Asked about Mr McCluskey’s timeframe, Ms Thornberry appeared to get in a muddle with her response as she told host Snow: “…Well, I don’t think we need to have – oh I’m just thinking.”
“That’s quite a thought,” Snow fired back.
“No, no, no hang on,” Ms Thornberry retorted before Snow once again asked: “How the hell are you going to put Labour back on top of the polls?”
Becoming ever more tetchy, the Labour MP once again tried to respond, before Snow shouted: “What about a new leader?”
As tempers began to rise further, Ms Thornberry appeared to snap, as she gave Snow a glaring looking and said: “Ok, do you want me to speak?”
The shadow minister defended her party's floundering poll performance
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Silencing Snow, she continued: “We could start with maybe a month, maybe two months of not arguing and deciding who it is we should be fighting against, not against one and other, but that actually we should be holding the Tories to account.
“This is a dreadful government and it is our job to hold them accountable and that’s what we should be doing.
“When we start focussing on that, then things will start to change and the wheel will turn.”
Corbyn looks crushed following by-election defeat Fri, February 24, 2017
Labour leader Jeremy Corbyn leaves his home following a humiliating blow by the Conservatives after snatching Copeland in a by-election victory. The struggling politician was talking on the day his party lost a by-election to the government, the first time this has happened in over 30 years.
Adam Gray / SWNS.com 1 of 10
Jeremy Corbyn is seen at Savoy Place in London where the Labour leader was giving a speech on Brexit
On Monday, the shadow Brexit secretary Sir Keir Starmer warned Labour would oppose any final deal on Britain's EU exit if it does not meet “six texts”.
During a speech at Chatham House in London, Sir Keir argued any deal must offer the “exact same benefits” the UK has from the single market and customs Union.
The call was echoed by Ms Thornberry, who told Channel 4: “We are a national party and the people said they wanted to leave the European Union and we will do as we are told.
“We voted to trigger Brexit, now the question is ‘what kind of deal?’ and we need to make sure that when these decisions are made we are looking after the economy.
“Any government’s first priority has to be the safety and security of its people, and its second priority should be the economy.”