This is crucial. Is it possible that Obamacare might actually work? Medicare and Medicaid are the two biggest drains on governmental funds by far. The only thing close is social security, which of course pays for itself for a couple of years yet. Slowing down or reversing the trend of huge increases in mandatory M&M funding every year is the first and most vital step to chipping away at that 14 trillion dollar debt we've shunted to the corner of the room.
Here is the Wikipedia page breaking down the 2013 budget.