I keep hearing Republicans...

...say that "we don't have a revenue problem, we have a spending problem." But Lori Montgomery writes in the Washington Post today (my emphasis):

The nation’s unnerving descent into debt began a decade ago with a choice, not a crisis.

In January 2001, with the budget balanced and clear sailing ahead, the Congressional Budget Office forecast ever-larger annual surpluses indefinitely. The outlook was so rosy, the CBO said, that Washington would have enough money by the end of the decade to pay off everything it owed.
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Together, the economy and the tax bills enacted under former president George W. Bush, and to a lesser extent by President Obama, wiped out $6.3 trillion in anticipated revenue. That’s nearly half of the $12.7 trillion swing from projected surpluses to real debt. Federal tax collections now stand at their lowest level as a percentage of the economy in 60 years.