Federal Reserve chairman Alan Greenspan has warned that allowing huge US budget deficits to continue could have "severe" consequences.
Pension and healthcare costs pose risks to the economy, Mr Greenspan said
Speaking to the House Budget Committee he urged Congress to take action to cut the deficit, such as increasing taxes.
While the US economy is growing at a "reasonably good pace" he warned that budget concerns were clouding the economic outlook for the US.
Pension and healthcare costs posed the greatest risks to the economy, he said.
The government program faces severe financial strains in coming decades as the massive baby-boom generation retires.
"I fear that we may have already committed more physical resources to the baby-boom generation in its retirement years than our economy has the capacity to deliver. If existing promises need to be changed, those changes should be made sooner rather than later," Mr Greenspan said.
He also warned that unless the nation sees unprecedented rises in productivity "retirement and health programmes would need "significant" changes.
He called on Congress to cut promised benefits for retirees, as the promised benefits for the soon-to-retire baby boom generation were much larger than the government could afford.
Meanwhile any move to narrow the deficit gap by raising taxes could pose a significant risk to the economy by dampening growth and spending, he added.
He also urged Congress to reinstate lapsed rules that require tax cuts and spending to be offset elsewhere in the budget in an effort to prevent the US heading further into the red.
Despite the dire warnings, Mr Greenspan did offer some good news for the short term.
As US growth gathers steam and incomes rise that should lead to a narrowing of the deficit.
Recent increases in defence and homeland security spending were also not expected to continue indefinitely, which should cut some costs.
Since President George W Bush came to office the federal budget has swung from a record surplus to a record deficit of $412bn last year.