Refusing to cut public spending would be a "betrayal" of progressive values, Nick Clegg has claimed.
The deputy prime minister argued in a speech designed to pave the way for tough economic action that cutting the deficit is the only way to return to spending money on schools and hospitals.
"This government, Liberal Democrats and Conservatives together, will not allow our hands to be forced by the markets," he pledged.
"We're going to see through the deficit production plan that will turn Britain's fortunes around."
he argument compliments a recent David Cameron speech in which he repeatedly drew attention to interest payments as a symbol of Britain's economic malaise.
"Make no mistake; this is not a task we relish, nor is it our choice," he added.
"This is the legacy that we as a new government and we the British people were left. Left by a government bankrupt of ideas and very nearly bankrupt. It is the only way we can get our public finances on a sound footing."
Mr Clegg argued spending cuts were progressive because the pursuit of social justice while taxpayers' money is spent paying the interest on "Labour's debt" was impossible.
"We have to set out a plan now so we can take control of our own future by taking action, by being responsible," he continued.
"By taking action, we do something hugely important - we give ourselves the chance to shape outcomes, to do all we can to bring down the deficit in a way that delivers fairness, to protect those who need it most."
The argument compliments a recent David Cameron speech in which he repeatedly drew attention to interest payments as a symbol of Britain's economic malaise.
Mr Clegg attended the Nueva Economia Forum in Madrid last week. He said teh Spanish government had seen the premium on bonds compared to German bonds jump from 0.5% to two per cent.
"As the nation with the highest deficit in Europe in 2010, we simply cannot afford to let that happen to us too," he warned.
The deteriorating situation in Europe was used as the reason for the dramatic shift in Mr Clegg's own views on the situation, as he explained why he had not demanded immediate cuts during the general election campaign.
"The world has changed since the days people advocated a looser fiscal policy. We need to adapt to those changing circumstances and change our fiscal position, too," he said.
"The choices that were available to us just two months ago are no longer available. We have to take action now so that we can still be in control of our future."