Via Marc Ambinder, former President Bill Clinton warns reformers--namely, his fellow Democrats--not to treat the Congressional Budget Office as gospel:

"I recognize that if you're in that budget office, you've got to project the future," Clinton said. But certain programs would realize savings "regardless of whether the mathematical rules they are now up with will prove it or not." He said that those with a stake in changing the system "almost always get the short end of the stick" when it comes to budget projections. "In Washington, we strain a lot of gnats while we''re swallowing camels."  Lost in the debate about how much health care reform will cost, Clinton said, is the debate about whether the reforms will work.

The CBO famously made it tough for Clinton and his allies back when they were trying to pass health reform. And, by all accounts, the CBO has played a more constructive role this time. Still, it's important to realize that CBO projections are just that: Projections. And particularly when you're talking about the possible political behavior of Congress and appointed experts in ten or twenty year, the uncertainty level is high.

By the way, Clinton's last point--about what's being lost in the discussion about costs--is incredibly important. More on that soon...

--Jonathan Cohn