A. Dramatically cut defense spending, Medicare Spending, or reduce Social Security Benefits.
B. Increase taxes to raise revenue to pay for the increased costs of these entitlements
There is no other way to balance the budget. Anyone who tells you that it is possible to solve the budget gap through "eliminating pork projects" is speaking nonsense: earmarks account for less than 1% of the current federal deficit. A serious attempt to reduce the deficit will have to either increase taxes or dramatically reduce health care costs.
So how do we get to this point? See for yourself! The New York Times has put together a great tool that allows anyone to "fix the budget" themselves through a simple online tool. This allows you to cut programs, increase taxes, or close tax loopholes in order to see the programs that really impact the budget deficit. This shows you the real impact of various proposed tax increases and spending cuts on the projected budget deficits in 2015 and 2030. I was surprised to see that many of the programs which receive the most talk on the political news shows (such as congressional earmarks) have a negligible impact on the budget, where as small changes such as raising the age one can receive social security benefits can add up to hundreds of billions of dollars over the course of 20 years.