A draft report from the Democratic Leadership Council, leaked to the Washington Web site Politico Wednesday, contends that while Obama, a freshman U.S. senator from Illinois, will likely increase turnout from blacks, self-described liberals and young voters, it may not be enough to offset weaknesses among middle-class white voters, particularly men.

Those votes will be necessary for Obama to defeat Republican opponent Sen. John McCain of Arizona, the study says. It contends that Obama hasn't done enough to change the Democratic Party's historic weakness in that group, and that past election results suggest seeking to balance out the situation by recruiting new voters won't be sufficient.

"There has been so much emphasis on new entrants in the electorate, and this report is historic and not predictive, but history tells us it would be an unusual circumstance if we witnessed a massive shift in the electorate," Politico quoted the DLC analysis as saying.

It defined these white voters as typically between 30 and 59 years old and living in a suburb or the rural South or Midwest.