The Government Accountability Office, which audits federal spending, has concluded that the national debt would rise precipitously if President Obama's health care legislation doesn't go into effect.

A report titled "The Federal Government's Long-Term Fiscal Outlook" states that several parts of the health plan "were designed to control the growth of health care costs. The full implementation and effectiveness of these cost-control provisions... would slow the growth in federal health care spending over the long term."

If the legislation were thrown out, though, the forecast becomes considerably more gloomy. The report does not go into detail about the consequences of an invalidated law — but as TPM reports, it clearly implies that "if key cost-control measures in the law, and other automatic cuts to Medicare spending baked into current law, are ignored, or overridden by Congress, the implications for the national debt are vast."

Or, in the dry language of the GAO:

These concerns are reflected in our Alternative simulation, which, consistent with CBO’s and the CMS Actuary’s alternative scenarios, assumes that certain cost-containment mechanisms are not sustained over the long term. Spending on health care grows much more rapidly under this more pessimistic set of assumptions. Absent changes to these programs, spending on Medicare and Medicaid under the Alternative simulation grows to over 8 percent of

GDP by 2030.

The health care bill's fate rests in the hands of the Supreme Court, which is expected to rule on its constitutionality in June. On Monday, President Obama expressed confidence that the court would uphold his signature legislative achievement.