The campaign on Sunday released a breakdown of how it got to the $5 trillion number. It counted $2.5 trillion from Romney's plan to lower rates by 20 percent across the board. It included $1.1 trillion from a corporate tax cut, and $150 billion from a repeal of the estate tax, among other things.
"Even the studies that Romney has cited to claim his plan adds up still show he would need to raise middle class taxes," the campaign said in a statement -- claiming Princeton economist Harvey Rosen found "paying for Romney's tax cuts would require large tax increases on families making between $100,000 and $200,000."
Rosen, though, told The Weekly Standard
that he "can't tell exactly how the Obama campaign reached that characterization of my work."
His study took into account "additional income" that could be generated by economic growth under the plan. Rosen wrote in the study that "under plausible assumptions," a Romney-style proposal "can both be revenue neutral and keep the net tax burden on high-income individuals about the same. That is, an increase in the tax burden on lower and middle income individuals is not required in order to make the overall plan revenue neutral."
The Obama campaign's math also includes corporate tax cuts -- though Obama, too, has called for a corporate tax cut. The major difference between them is just that Obama wants to bring the top rate from 35 to 28 percent, while Romney wants to bring it to 25 percent.