Dozens of hardline Labour MPs will work with the SNP to hold Ed Miliband to ransom and stop him making any cuts to public spending , it was claimed today . The left-wingers have pledged to vote against any Budget that includes austerity measures to tackle the deficit . John McDonnell , chair of the Socialist Campaign Group of Labour MPs , said ‘ a bloc of 30-40 left MPs ’ in Labour will ensure Mr Miliband will not be able to ‘ ignore ’ their demands . Scroll down for video . Former First Minister Alex Salmond - who is standing for the SNP in Gordon , was out campaigning today . Mr Salmond has boasted that the SNP will hold the balance of power in the Commons after the next election . SNP leader Nicola Sturgeon has said that she has already been in contact with MPs on the left of the Labour Party to plot how they could work together . Former First Minister Alex Salmond , meanwhile , has boasted that the SNP will hold the balance of power in the Commons after the next election and will be able to force Labour to increase spending , borrowing and debt . Mr McDonnell has held talks with Mr Miliband and said he has already ‘ moved the party on to our agenda ’ . In a recent meeting , he told Mr Miliband that any government he leads could be ‘ the most radical ’ and ‘ perhaps more radical ’ since Clement Attlee . He claimed Mr Miliband had agreed . Mr McDonnell said that if Labour falls short of a majority it would have to abandon its pledge to impose spending cuts because of the pressure from left in the party . Ed Miliband will struggle to stop dozens of hardline Labour MPs from working with the SNP to stop cuts to public spending , it was claimed today . He told the New Statesman : ‘ The first row will be around austerity unless we get this right ... I think it will change , inevitably it will change . ‘ I think it will be clear from pressure coming back from constituencies and individual MPs that we need a Labour government quickly making a change. ’ Mr McDonnell said there has already been ‘ a shift in terms of the Labour leadership ’ s thinking and even in terms of Ed Balls ’ s thinking ’ . He added : ‘ You ’ ve got to offer an alternative . You can ’ t come in with austerity-lite , it won ’ t work . John McDonnell said ‘ a bloc of 30-40 left MPs ’ in Labour will ensure Mr Miliband will not be able to ‘ ignore ’ the hard-left in the party after the election . ‘ Coming in with arguments that you ’ re going to cut services , not necessarily as much as the Tories , but you will still be cutting services , I think that argument is beginning to creak , I think that argument is beginning to fade . ‘ Increasingly now , the Labour leadership has recognised that , actually , you can tackle the deficit over a longer period of time , that way you avoid any cuts whatsoever. ’ Mr McDonnell said that a ‘ large number ’ of Labour ’ s candidates for the General Election were on the left and could help vote against the renewal of Trident . He added that he is ‘ more optimistic now about the role of the left in the Labour Party than at any time in the last 20 years ’ . Tory chairman Grant Shapps said : ‘ This is the true face of Ed Miliband ’ s Labour Party : they ’ re addicted to more wasteful spending and more taxes . 'If Ed Miliband becomes Prime Minister he ’ ll be carried there by Alex Salmond , bankrolled by Len McCluskey and pushed around by his own backbenchers . It would cause chaos for Britain. ’ Mr Miliband has ruled out the possibility of going into a formal coalition with the SNP , but the two parties could agree a post-election deal . Labour peer Baroness Prosser today said that the two parties could work together on an issue by issue basis . She told the BBC ’ s Daily Politics : ‘ I think that is just how pragmatic politics works. ’ On Sunday , Miss Sturgeon said the SNP could be in a 'very powerful position ' at Westminster after the election . Mr McDonnell , 63 , who has been the MP for Hayes and Harlington since 1997 , is chair of the Socialist Campaign Group and Public Services Not Private Profit Group . Scottish First Minister Nicola Sturgeon on the campaign trail at Glasgow Fort shopping centre today . In 2010 , he announced his intention to stand for the party leadership following the resignation of Gordon Brown , but later decided instead to back Miss Abbott ’ s unsuccessful leadership bid . He rebelled against the government on controversial votes , such as the Iraq war and top-up fees . Mr McDonnell , who left school at 17 , served as a National Union of Miners and TUC official , before being elected to the Greater London Council in 1981 , where he served as Ken Livingstone ’ s deputy . In November last year he was criticised after he joked about how people in Tory minister Esther McVey ’ s Wirral West constituency had asked why they were not ‘ lynching the b****** ’ .
Left-wing MPs pledge to vote against any Budget that includes austerity . John McDonnell said there 's ' a bloc of 30-40 left MPs ' against cuts . Nicola Sturgeon claims she has already been in contact with Labour MPs . Alex Salmond has boasted that the SNP will hold the balance of power .