Leave it to one of the country's top economists to fill in Congress on how a key federal agency works.

During a Wednesday morning House Budget Committee hearing on the nation's long-term economic future, Rep. Tom McClintock (R-Calif.) pressed Congressional Budget Office Director Douglas Elmendorf on the past.

McClintock asked Elmendorf about a budget the same committee had passed four years ago, wondering what the effects would have been in 2014 and beyond had it gone into law. Elmendorf explained that the CBO does not estimate the effect of budget resolutions.

"But you had projections in terms of how much revenue would be coming in, how much spending would be done, how much deficit there would be," McClintock pushed back. "What was your projection?

"We have projections under current law," Elmendorf responded. "We never had a projection under the budget resolution. We don't do those estimates directly. I think the committees often draw on sets of estimates that we've done. But we don't tote up the resolution and say what would happen. So we don't have those numbers."

More from the CBO's website on its role in budget resolutions:

CBO does not analyze or prepare estimates of budget resolutions because they are targets for the Congress and its committees and do not contain legislative language for specific proposals whose budgetary effect we could estimate. Thus, CBO makes no assessment of the budget deficits or the amounts of spending and revenues that would result from any budget resolution approved by either of the budget committees.

Rep. Earl Blumenauer (D-Ore.) piled on at a later moment during the hearing, commending Elmendorf for his reminder to McClintock.

"I'm pleased that you're helping my friend from California remember that you don't score resolutions," Blumenauer said.

Watch the exchange above.