Overwhelmingly: the GOP and Bush, a fact the vast majority of the right simply ignored for the past eight years. Leonhardt lays out the facts that Glenn Reynolds and his fellow partisans keep denying:

David's bottom line:

About 33 percent of the swing stems from new legislation signed by Mr. Bush. That legislation, like his tax cuts and the Medicare prescription drug benefit, not only continue to cost the government but have also increased interest payments on the national debt.

Mr. Obama’s main contribution to the deficit is his extension of several Bush policies, like the Iraq war and tax cuts for households making less than $250,000. Such policies together with the Wall Street bailout, which was signed by Mr. Bush and supported by Mr. Obama account for 20 percent of the swing.

About 7 percent comes from the stimulus bill that Mr. Obama signed in February. And only 3 percent comes from Mr. Obama’s agenda on health care, education, energy and other areas.

If the analysis is extended further into the future, well beyond 2012, the Obama agenda accounts for only a slightly higher share of the projected deficits.