75% or more of the current deficits are due to the great recession.
Tax revenue is down but expenses (more people applying for SS early, more medicaid, more UI, more food stamps, etc) are up.
Before the recession hit the deficit was 100-400 billion a year. If the economy were still doing ok it would still be 100-400 billion a year. So overcoming the recession is the most important thing.
After that, minor changes could fix the deficit over the short term. A 200-400 billion shortfall isn’t impossible to fix by any means. If we hadn’t had the 2001/2003 tax cuts and the war in Iraq, there would’ve been almost no deficits from about 2001-2007, so realistic policy changes could make a huge difference. Tax hikes and spending cuts can correct a deficit that is 1-3% of GDP, which is what the deficit was before the recession and what it will likely be after.
Over the long term (100 years or so) we are going to face large debts due to our health care system. Medicaire, medicaid, etc. So drastic reforms to improve efficiency and cost effectiveness of health care are important.
But anyway, the recession is the most important factor in short term deficits, and health care the most important in long term deficits. Trying to fix the debt problems by cutting discretionary spending, or cutting 50 billion from XYZ won’t matter if the recession is still going strong and health care is still insanely expensive.