Look at it carefully. As bad as Bush's two terms were (about a five trillion dollar increase in the national debt), Obama has managed to exceed that with a more than six trillion dollar increase in less than one and a half terms. As much as some like to blame the Iraq War, this was only (and I'll try not to gasp as I write this), $709 billion -- less than Obama's much vaunted stimulus package, and at most only about 14% of what Bush contributed to the national debt. Doubtless, Democrats will blame the problem on low tax rates, and that certainly contributed. But notice that revenues actually rose until the economy collapsed in 2008.
The core problem is that the corruption of the political class in America, in both parties, makes it easier to give out goodies, usually to those who are already rich, than to say no to them. Money given out to the poor is a pretty tiny fraction of the problem, but it is what enables Democrats to keep pretending that they are the party of the poor, instead of what they are: the party of Wall Street and green looters of the Treasury.
UPDATE: What is really tragic is how easy it would be to fix this. Here is a spreadsheet from the White House Office of Management and Budget that shows budgets in inflation adjusted dollars from 1940 through estimated 2018. If the federal government would spend what it did in 2006 (you know, while we were fighting a costly war in Iraq), $2.655 trillion a year, combined with the 2013 estimate for receipts (2.712 trillion a year), we would have a balanced budget -- actually, a slight surplus. Sure, we have more people out of work today than in 2006, and the government spends more on unemployment and various support programs -- but we are not fighting a war in Iraq, either.