Ed Miliband is in league with the Scottish Nationalists and preparing to allow them to be ‘ the chain to Labour ’ s wrecking ball ’ , David Cameron will say today . The Prime Minister – who last night said he would be a ‘ big failure ’ if he does not win a Commons majority – will unveil an analysis to show Labour and the SNP are ‘ really on the same side ’ and want ‘ more borrowing , more debt and more taxes ’ . Mr Cameron will show that , since Mr Miliband became Labour leader , the SNP has trooped through the lobbies with his MPs in 91.5 per cent of Commons divisions . The SNP backed Labour in 27 out of 28 votes on welfare and 62 out of 65 on the economy . Warning : David Cameron will unveil analysis to show Labour and the SNP are 'really on thre same side ' today . Labour and the SNP have ruled out a formal coalition but refused to do the same for a looser arrangement that would prop up a minority government led by Mr Miliband . The Prime Minister last night told BBC Newsnight presenter Evan Davis that he would feel he had ‘ not succeeded ’ if the Conservatives failed to win a majority . His intervention today will pile pressure on the Labour leader ahead of tonight ’ s TV ‘ challengers ’ debate ’ , in which he will square up to SNP leader Nicola Sturgeon . Miss Sturgeon ’ s performance in the first TV debate has seen her party surge further , breaking 50 per cent in one poll and threatening Labour with wipeout north of the border . Since Mr Miliband became Labour leader , the SNP has trooped through the lobbies with his MPs in 91.5 per cent of Commons divisions , Cameron will say . Yesterday , she suggested she would seek to hold Labour to ransom on a vote-by-vote basis , insisting : ‘ It ’ s perfectly possible to defeat governments on issues and to change the course of governments on issues without bringing the government down. ’ Even senior Labour figures have doubts over Mr Miliband ’ s decision to be the only leader from the main Westminster parties to appear with Scottish and Welsh nationalists , the Greens and Ukip , putting him in danger of being outflanked on all sides . A Labour source said : ‘ Our best hope is that nobody watches it and it ’ s just a damp squib . Other than that , we ’ re hoping the media narrative is that Cameron was right to sit this one out , not that Ed looked like an idiot. ’ Mr Cameron , launching his party ’ s Scottish manifesto in Glasgow , will say Scotland is the scene of a ‘ massive political fight ’ that could determine the future of the UK . ‘ We ’ ve got Labour and the SNP on opposite sides – slugging it out – but if you take a step back they ’ re really on the same side , ’ the Prime Minister will say . ‘ You have a weak Labour party , who want more spending , more borrowing , more debt and more taxes . And the people who will prop them up , the SNP – who want even more spending , more borrowing , more debt and more taxes . ‘ Together , they pose a clear threat to the future of our United Kingdom : a coalition of chaos . The SNP acting as the chain to Labour ’ s wrecking ball , running right through our economic recovery – and it will be you who pays the price. ’ The Conservative analysis shows that , in 319 votes between 2010 and 2015 , Mr Miliband trooped through the voting lobbies with SNP MPs on 292 occasions . Labour and the SNP ( pictured , SNP leader and First Minister Nicola Sturgeon ) have ruled out a formal coalition but refused to do the same for a looser arrangement that would prop up a minority government led by Miliband . David Cameron told BBC Newsnight presenter Evan Davis he will have failed as Tory leader if he does not win a majority at the next election . Labour and the Scottish Nationalists joined forces to oppose Government policies to rein in benefits and reward work . Both parties also voted against capping benefits to stop people taking home more in welfare than the average family earns in employment . Miss Sturgeon hailed tonight ’ s challengers ’ debate as ‘ another opportunity to take the SNP ’ s positive message on the progressive policies we believe in to people right across the whole of the UK ’ .
David Cameron will unveil analysis to show Labour and SNP 'on same side ' He 'll say since UK became Labour leader SNP trooped through lobbies . SNP backed Labour in 27 of 28 votes on welfare and 62 of 65 on economy . Labour and SNP ruled out formal coalition but refused same for looser term .