A Congressional Budget Office's (CBO) report on healthcare was a "devastating blow" to the bill's prospects, a key centrist Democrat argued Friday.

Sen. Ben Nelson (D-Neb.), whose vote will be critical to passing a final healthcare reform bill through the Senate, condemned the House version of the bill, which institutes a surtax on wealthy Americans to finance the $1 trillion bill, as creating "class warfare."

"I think it's a devastating blow," Nelson said of the import of the CBO analysis this week that the House healthcare reform proposal would worsen the fiscal situation of the U.S. over time.

"The CBO is sort of an official umpire -- they don't take sides," Nelson said during an appearance on CNN Radio. "And when they come out with a recommendation or a study, you know it doesn't have a political bent to it at all."

The Nebraska centrist also characterized the proposed surtax to finance health reform as an unfair way of paying for the new system.

"I know it's going to be difficult to find a way to finance the additional millions of Americans into the healthcare program...and what we have to do is find a way that's fair," Nelson said. "And it's not fair to single out and create class warfare to do it."

And as the August recess quickly (and the self-imposed deadline for passing preliminary legislation in the House and Senate) approaches, Nelson worried that by imposing the deadline, the Senate had created "self-fulfilling failure."