It was the most startling of warnings. If the U.S. does not get its finances in order “we will have a European situation on our hands, and possibly worse”, claimed Paul Ryan, the new Republican chairman of the House of Representatives budget committee.

As it stands today, the U.S. borrows about 40 cents of every dollar it spends. Curbing the budget deficit has been the stated mission of Mr. Ryan, a rising Republican star, for several years. But such calls for action have multiplied in Washington in recent months, igniting what some say is the fiercest debate over fiscal and budgetary policy in decades.

The risks are big. If the government rushes into austerity, cutting too much and too quickly, it could stunt economic recovery. But if the political system cannot forge some kind of consensus on steps to restore U.S. deficits to sustainable levels, the danger is potentially even greater: a sovereign debt crisis in the world’s largest economy.

“It’s a weak period for the economy, so I don’t think you want to do serious deficit reduction anyway, but we are playing a dangerous game and we will start to pay a price for fiscal irresponsibility,” says Ethan Harris at Bank of America Merrill Lynch.

The big fear is that if no action is taken, investors might eventually punish the US for its fiscal laxity. That would raise borrowing costs for businesses and consumers, force severe austerity measures and risk social unrest. Not only America’s triple-A credit rating could be threatened; some point to consequences in foreign affairs and defence as well. Mike Mullen, chairman of the joint chiefs of staff, last year warned that the debt pile could limit the flexibility of the US in funding its military – in his eyes the “most significant threat to our national security”.

So far, capital markets have not reacted much to the dismal long-term outlook. The 10-year Treasury yield, for instance, has been trading this week well below 3.4 per cent, close to historical lows although it has risen in recent months. Still, a growing number of voices are calling for a deal to address America’s strained public finances, even if it means tackling programs such as retirement benefits and health care for the elderly that have long been protected.

Yet whether this anti-deficit rhetoric translates into a meaningful turn towards austerity in the coming months – and leading into the 2012 presidential election – is much in doubt, for two main reasons: severe political divisions and the continuing fragility of the economic recovery.

“It’s not urgent but at some point it’s going to become more urgent,” says Phillip Swagel, who was a senior economic official in the George W. Bush administration. “Clearly the markets don’t think we’re Argentina, but we should send them a signal that they are right, that we will address the issue.”

A deal extending Bush-era tax cuts and unemployment benefits in December failed to send that message, adding $858-billion to long-term deficits without any commitment to reductions in the future, even though supporters argue that if the measures boost growth, America’s budgetary position will improve too.

But more big tests of America’s commitment to fiscal discipline are looming. On Jan. 25, President Barack Obama will lay out his legislative priorities for 2011 in his State of the Union address to Congress, and measures to reduce long-term deficits are expected to be on the agenda.