If Congress decided to do nothing about the deficit beginning right now, the budget would be balanced by the end of the president's would-be second term. According to the CBO, if Congress allowed the Bush tax cuts to expire and disallowed more tax cuts, while also discontinuing the "doc fix" for Medicare -- no more deficit. In convenient chart form:
The top chart represents the "do nothing" approach, while the bottom chart shows expenditures with tax cuts in the mix.
Of course, doing nothing isn't an option. All things considered, Congress has to do something about the economy at this point, preferably more stimulus spending. But continuing to cut taxes is obviously a mistake because it won't be stimulative and it won't reduce the deficit. Hence the Republican sabotage, etc, etc. The Republicans simply aren't interested in reducing the deficit or fixing the economy. At all.