The Tories today goaded Keir Starmer's 'Government on life support' as Labour Cabinet ministers were warned they face the sack under Andy Burnham.Claire Coutinho, the shadow energy secretary, sought to exploit Labour's leadership chaos in House of Commons clashes with David Lammy, the Deputy Prime Minister.Mr Lammy and Ms Coutinho were standing in for their party leaders - Sir Keir and Kemi Badenoch, respectively - during Prime Minister's Questions on Wednesday.Sir Keir, who is at the G7 summit in France this week, is facing a looming challenge from Mr Burnham if the Greater Manchester mayor wins tomorrow's parliamentary by-election in Makerfield.Ahead of Thursday's vote, Ms Coutinho put Sir Keir's Cabinet ministers on notice they are facing the chop under a Mr Burnham premiership.She also mocked those disgraced ex-ministers who are being touted for a return to the Government if Mr Burnham enters Downing Street in the coming weeks.And Ms Coutinho asked why 'out of control' Energy Secretary Ed Miliband had not yet been sacked, amid claims he has 'ghosted' Sir Keir during Labour's furious row over defence funding.'This is a Government on life support,' the Tory frontbencher told MPs. Claire Coutinho, the shadow energy secretary, sought to exploit Labour's leadership chaos in House of Commons clashes with David Lammy , the Deputy Prime Minister. Mr Lammy and Ms Coutinho were standing in for their party leaders - Sir Keir and Kemi Badenoch , respectively - during Prime Minister's Questions on WednesdayWith the prospect of Mr Burnham soon being chosen as Sir Keir's successor by Labour MPs, Ms Coutinho ridiculed Mr Burnham's rumoured picks for his Cabinet.Ms Coutinho added: 'And what's their grand plan now?'They want to - let me get this straight - they want to make the job-destroying Energy Secretary (Mr Miliband) the Chancellor.'They want to bring back the former transport secretary (Louise Haigh) who resigned for nicking phones.'They want to replace him (Mr Lammy) with the former deputy prime minister (Angela Rayner) who resigned for dodging taxes.'In a swipe at Sir Keir's existing Cabinet - who sat alongside Mr Lammy in the Commons - Ms Coutinho told Labour ministers they face being axed by Mr Burnham.'If the mayor of Manchester gets his way, I'm pretty sure half the front bench are going to be getting a pay cut pretty soon,' she said.Ms Coutinho went on to slam the manoeuvring within Labour ranks as a 'pointless distraction'.She reiterated the Tories' demand for Labour to slash benefits in order to boost defence spending, as well as to scrap its Net Zero agenda to secure cheaper energy.Earlier, as she opened the exchanges with Mr Lammy, Ms Countinho said she was privileged to be standing with 'one of the few survivors of Labour's original Cabinet'.The shadow energy secretary went on to claim Mr Milband's block on new North Sea oil and gas drilling was 'destroying' well paid jobs in Scotland.On the eve of the Aberdeen South by-election, also being held on Thursday, Ms Coutinho accused Mr Lammy of being more willing to take oil from Russia or Qatar than Aberdeen.Mr Lammy replied that Ms Coutinho had renounced her previous commitment to Net Zero when she was energy secretary in Rishi Sunak's Tory government.He added: 'The PM and the Energy Secretary have been discussing cutting bills by over £100.'We've got our warm homes plan, lifting millions of families out of fuel poverty and securing enough energy projects to power 23 million homes.'She was the energy secretary who left our country exposed to global fossil fuel markets, we're delivering clean energy security.'Ms Coutinho said the Tories had brought down bills by £500 under her, whereas they had risen £300 under Labour.She added: 'This is nonsense. His party are banning new oil and gas licences in the North Sea and… this is the same policy that the SNP championed for years.'This is pointless virtue signalling and is destroying well paid jobs.'Mr Lammy replied that 700 jobs had been lost in the industry over the last decade, and production has fallen by 75 per cent since the Millennium.He said the Government had attracted over £900billion of investment in renewables, and 100,000 jobs in Scotland were linked to clean power.The Deputy PM later told her to 'stop reading the papers', as she referred to reports Mr Miliband 'ghosted' Sir Keir by refusing to meet with him to discuss cuts to his department to help fund a boost to defence spending.Ms Coutinho said: 'The world is getting more dangerous, yet last week the PM asked the Energy Secretary to help fund the defence of our country and he ghosted him.'Let me repeat that, the Energy Secretary refused to meet the PM on a matter of national security. Why hasn't he been sacked?'Mr Lammy insisted Labour's long-delayed Defence Investment Plan 'will set out how every Government department is contributing to defence, including the energy department, we will always put national security first'. A Downing Street spokeswoman said the reports that Mr Miliband 'ghosted' Sir Keir 'aren't true', but was unable to give details on when the pair last spoke.'They speak regularly and are working closely together on the issues that matter to British people,' the spokeswoman said.