Via Ezra Klein, here's a chart showing the CBO projection for the National Debt at the beginning of the Bush administration, given the surplus and the continuation of Clinton era policies, and the actual debt throughout the last 10 years.
Ezra summarizes:
There are two major takeaways from this report. The first is that the current deficit is primarily, though not exclusively, the result of policy decisions made during the Bush years. Insofar as Obama deserves blame for current deficits, it’s mainly because he hasn’t shut down Bush-era policies like the tax cuts. All the stimulus spending combined accounts for a relatively small portion of the deficit. Conversely, the financial crisis began before Obama was in office, but is unquestionably the single largest contributor to the deficit while he’s been in office.
The second is that economic projections are uncertain at best. Without the financial crisis, our current deficits, though significant, would be much more modest. Conversely, if economic growth takes off in the coming years, or if a series of disruptive innovations and policy reforms substantially slow the growth of health-care costs, our future deficits will be much smaller than we currently project. What we control are our choices. And with the exception of the health-care reform law, few of our post-Clinton choices have been good for the deficit.
However, the CBO is as close to a neutral arbiter of the budget and the debt. We shouldn't write off its projections since doing so would leave us without this crucial referee.
That said, I find it constantly hilarious that suddenly -- in the wake of a massive recession -- the Republicans are worried about the debt. Look at that chart again. Until 2009, they barely ever mentioned the word "debt."