Herewith Jason Furman, courtesy of the U.S. Treasury Department.
I suppose they'll have to fire the real economists there and find people who are willing to make false estimates.
Just as clarification, the Laffer Curve is an economically valid idea. Only, for taxing labor income (the main component of the income tax), rates might have to go up to 80 or 90 percent before it would start to apply. So it's not exactly relevant with regard to the Bush tax cuts. (For capital gains, by contrast, the Laffer Curve may kick in at 30 to 40 percent, although it's hard to disentangle temporary from permanent effects.)