In 31 months of Barack Obama’s presidency, according to the Treasury and CBS News, the US has added $4 trillion to its national debt. That approaches the presidential record set by George W. Bush of $4.9 trillion, but there’s a catch to that. Bush set that record in two terms — in 96 months:

The latest posting by the Treasury Department shows the national debt has now increased $4 trillion on President Obama’s watch. The debt was $10.626 trillion on the day Mr. Obama took office. The latest calculation from Treasury shows the debt has now hit $14.639 trillion. It’s the most rapid increase in the debt under any U.S. president. The national debt increased $4.9 trillion during the eight-year presidency of George W. Bush. The debt now is rising at a pace to surpass that amount during Mr. Obama’s four-year term.

Let’s cast this by month rather than by year. Bush added an average of $51 billion a month to the national debt. In his 31 months in office, Obama has added to the national debt at an average monthly rate of $129 billion. That is 152% more per month than Obama’s predecessor.

Mark Knoller lists Obama’s excuses for the debt buildup on his watch, which not surprisingly all get blamed on Bush:

“two wars we didn’t pay for”

“a prescription drug program for seniors…we didn’t pay for.”

“tax cuts in 2001 and 2003 that were not paid for.”

Well, there are big problems with these excuses, chief among them that none of this explains the sharp difference between the rate of debt under Bush and under Obama. After all, the wars all started early in Bush’s tenure. So too did the tax cuts and the Medicare Part D program. Yet not only did deficit spending remain under control throughout almost all of the Bush years, deficit spending actually declined in Bush’s second term until the economic collapse occurred.

So what changed? We’re spending more on entitlements, for one thing, but not that much more. Byron York argues that while conservatives are rightly focused on entitlements to solve the long-term structural deficit, the rapid short-term increase in deficit spending is the result of a Democratic spending spree:

There’s no doubt federal spending has exploded in recent years. In fiscal 2007, the last year before things went haywire, the government took in $2.568 trillion in revenues and spent $2.728 trillion, for a deficit of $160 billion. In 2011, according to Congressional Budget Office estimates, the government will take in $2.230 trillion and spend $3.629 trillion, for a deficit of $1.399 trillion. That’s an increase of $901 billion in spending and a decrease of $338 billion in revenue in a very short time. Put them together, and that’s how you go from a $160 billion deficit to a $1.399 trillion deficit. But how, precisely, did that happen? Was there a steep rise in entitlement spending? Did everyone suddenly turn 65 and begin collecting Social Security and using Medicare? No: The deficits are largely the result not of entitlements but of an explosion in spending related to the economic downturn and the rise of Democrats to power in Washington. While entitlements must be controlled in the long run, Washington’s current spending problem lies elsewhere. … Spending for Social Security and Medicare did go up in this period — $162 billion and $119 billion, respectively — but by incremental and predictable amounts that weren’t big problems in previous years. “We’re getting older one year at a time, and health care costs grow at 7 or 8 percent a year,” says Holtz-Eakin. If Social Security and Medicare were the sole source of the current deficit, it would be a lot smaller than it is. The bottom line is that with baby boomers aging, entitlements will one day be a major budget problem. But today’s deficit crisis is not one of entitlements. It was created by out-of-control spending on everything other than entitlements. The recent debt-ceiling agreement is supposed to put the brakes on that kind of spending, but leaders have so far been maddeningly vague on how they’ll do it.

Finally, let’s recall that Congress passes budgets, not the President. The proper measure of deficits and debt should be allocated on the basis of Congressional control as well as control of the White House. Ten months ago, when Obama blasted through the $3 trillion debt mark, I calculated the true allocation of debt along those lines:

First, let’s break down the last 10 years of the Bush/Obama era by control of Congress, starting on January 1, 2001. The starting point for the national debt was $5.662 trillion. On January 6, 2007, when Democrats took over, Republicans in total control had added $3.011 trillion in debt in six years, just slightly less than Obama has added since taking office less than two years ago. Since taking control of Congress less than four years ago, Democrats have added $4.992 trillionto the national debt. Perhaps it would be more fair to look at the entirety of Republican control of the House, which lasted 12 years and bridged the Clinton and Bush administrations. In that entire span, Republican budgets added $3.873 trillion to the national debt. That is not only far below what Democrats have added in just one-third of the time, it’s also far below the Obama administration’s own projections of how much they will add to the national debt in just one term. We can also do the same calculations by fiscal year, from October 1 to September 30 each year, matching the budgets. Using that guide, we find the following scenarios: Republicans in control for 12 years: Added $4.034 trillion (avg $336.17 billion per year)

Republicans in control during Bush era: Added $3.201 trillion (avg $533.5 billion per year)

Democrats in control of Congress during Bush/Obama era: Added $4.603 trillion (avg 1.48 trillion per year)

Now, with an extra $1 trillion in ten months, we can change that last line to $5.6 trillion for Democrats in less than 4 years. It’s an astonishing explosion of federal spending, much of it in the increased regulation that’s strangling job growth. It’s no coincidence, after all, that this massive expansion in federal size and power accompanies an extended economic slump and a refusal of investors to put their capital to work.