From the WSJ article, Review & Outlook: The Road to a Downgrade:

Then came Mr. Obama, arguably the most spendthrift president in history. He inherited a recession and responded by blowing up the U.S. balance sheet. Spending as a share of GDP in the last three years is higher than at any time since 1946. In three years the debt has increased by more than $4 trillion thanks to stimulus, cash for clunkers, mortgage modification programs, 99 weeks of jobless benefits, record expansions in Medicaid, and more.

Courtesy of the Wall Street Journal