Labour is making a determined effort to woo business, with a promise to be active in support of the modernisation of the economy if returned to government.
In a speech to the CBI, shadow business secretary Chuka Umunna will brand David Cameron and George Osborne "roadblocks to reform" whose insistence that the state must "stand aside and leave it to the market" is harming UK firms.
Rejecting calls from Conservative backbenchers for the abolition of the Department for Business, Mr Umunna will promise to restore the ministry's position in Whitehall, giving it "real clout" of the kind it enjoyed when Lord Mandelson was the effective deputy prime minister under Gordon Brown.
Mr Umunna's intervention comes shortly after warnings from former prime minister Tony Blair and former foreign secretary David Miliband that Labour must not alienate business.
Mr Blair was reported to have told MPs earlier this month that the party cannot afford to go into the 2015 general election without the public backing of a single major business figure.
Mr Umunna will tell a CBI lunch that Britain needs a "new economy" to compete effectively with emerging powers in the globalised world. He will cite the case of Brazil, whose GDP overtook Britain's at the end of last year and where per capita income is predicted to overhaul the UK's by 2030.
And he will call for "a national mission where productive business and active government work together in partnership".
Mr Umunna is due to say: "We need a new set of policies to build a better, more responsible and productive capitalism, fit for our times and for the future - a New Economy to deliver the fairer outcomes at home and greater competitiveness abroad, for the British people and British business.
"As a nation, we have a job of work to do to modernise our economy. The market alone won't get us there; government alone can't do so either. But it must be a national mission where productive business and active government work together in partnership."
Mr Umunna will say that Conservatives, including the Prime Minister and Chancellor, are "outside the international mainstream" by failing to support those in business arguing for "a more productive capitalism".