(CNN) -- Sen. Rand Paul, the son of libertarian-leaning Republican Ron Paul, threw some red meat to the Republican National Convention crowd Wednesday night by counting up the increase in the debt under the Obama administration.
"President Obama's administration will add nearly $6 trillion to our national debt in just one term," said Paul, whom Kentucky voters sent to the U.S. Senate in 2010.
The national debt -- the cumulative tab run up by the U.S. government over its lifetime -- stood at $10.6 trillion when Barack Obama took office in January 2009. It's currently running at nearly $16 trillion, according to the Treasury Department. The Congressional Budget Office estimates project another $600 billion budget shortfall for the 2013 fiscal year. That would make a $6 trillion increase in a single term, as Paul says.
But there are some catches.
First off, Obama governed for much of the first nine months of his administration under the last budget of the Bush administration. But he did push an $800 billion-plus economic stimulus program through Congress early in his term, some of which was spent before that budget year ended in October. Bush's original budget proposal predicted a $407 billion deficit for 2009, but the final figure was $1.4 trillion, according to White House figures.
Spending has gone up under the Obama administration: For the 2011 fiscal year, the second full budget of Obama's term, the federal government spent about $3.6 trillion, according to the White House budget office. That's about $600 million more than in 2008, the last full year under the Bush administration.
But the budget gap has another element: Tax revenues have dropped during the 2007-2009 recession and remain lower than before. In the 2007 budget year, which ended shortly before the recession began, the federal government brought in nearly $2.6 trillion; that number fell to $2.1 trillion in 2009 and is projected to total $2.4 trillion by the time this budget year ends in September.
True, but incomplete. While budget shortfalls have added $6 trillion to the national debt since January 2009, some of that spending was already in the pipeline, and some of it is the result of the economic slump that has cut into tax receipts.
Matt Smith and Amy Roberts contributed to this report.