Kevin Drum insists that it's easy:
By 2030, the income-outgo gap is about 1.5% of GDP, so all you have to do is pick and choose from a menu of options that gradually raise revenue and cut benefits by a combined total of 1.5% of GDP. That's it. Your choices will depend a lot on your values and your priorities, but in the end the only thing you have to do is make sure the numbers add up. Simple.
The Dish 