1. The Bush tax cuts the biggest culprit for the large national debt is the 2001 and 2003 tax cuts under then-president George W. Bush. It is an estimated addition of $1.6 trillion to the national debt. The tax cuts are ongoing, so the tab for them builds every year.

2. Health care entitlements
Democrats "constantly harp" about the Bush tax cuts, but those rates were in place in 2007, and the deficit that year was one-tenth the 2011 budget shortfall of $1.6 trillion. So what has changed since then? Added "federal regulation, bureaucracy, and new Medicaid and other entitlements have pushed up federal spending by $1.1 trillion to $900 billion more than required by inflation. This down the road will account for "basically 100 percent" of our debt problem.

3. The Great Recession
Some of the spending gap came from factors outside the control of Congress and the White House. As the government spent heavily to boost the economy, it took in hundreds of billions less in tax revenue than expected, because the Great Recession eroded Americans' income and spending.

4. Medicare prescription drug benefit
Another piece of the cake: George W. Bush's addition of Medicare's prescription drug benefit. That has added $300 billion to the debt. Expanding entitlements like Medicare or Medic-aid is a particularly tempting way for Congress to run up debt. Since lawmakers don't typically map out a revenue strategy to fund those benefits, they are "shielded from the political costs of actually paying for the new programs."

5. The wars in Iraq and Afghanistan
The tab for the wars in Iraq and Afghanistan comes to $1.3 trillion, another major chunk of unexpected spending over the last 10 years. These wars had to be financed with borrowing, which keeps adding up to national