There has been much discussion surrounding the impending "fiscal cliff." So, what exactly is this? Well, it is a combination of items that effectively equate to about $600 billion in potential spending cuts and tax increases. This represents about 4% of US GDP. So, failing to address these issues would likely result in a deep, prolonged recession. Read a good summary here, American Action Forum.
Dolvin, Steven D., "Fiscal Cliff" (2012). All Chapters. 47.