ABC News’ The Note reports that the Romney campaign is serious about its chances in Pennsylvania, a closely divided state that Democrats have nonetheless won for the last twenty years:

All the body language from the Romney campaign suggests that they see Ohio as a long-shot. Instead, it is now Pennsylvania that paves their path to 270. The Keystone state has eluded plenty of industrious and hopeful Republicans before Romney. While the western and central parts of the state tilt red, the city of Philadelphia and its sprawling and populous suburbs are the key to winning the state.

This gets to Team Romney’s theory of the race. For Pennsylvania to be genuinely competitive, the composition of the elctorate needs to be whiter than is currently projected. At the moment, pollsters assume a voting pool similar to the one in 2008, when 74 percent of voters identified white, and 26 percent of voters identified as nonwhite. Pennsylvania was on the lower end of that — according to exit polls, African Americans, Latinos and Asian Americans were 18 percent of the electorate in the state. Romney is essentially counting on high turnout among whites — and lower turnout from African Americans and Latinos — to push Pennsylvania into the toss-up column. Then, he would have a chance to capture the state, and make up for his problems in Ohio. And if Team Romney thinks this is a real possibility, than they’re also counting on a whiter electorate nationwide.

The problem, of course, is that the public polls disagree on all counts. In its final poll, the Pew Research Center estimated that the 2012 electorate would look like the one in 2008: 74 percent white, 26 percent nonwhite. Pew’s result among likely voters? An Obama win, 50 percent to 47 percent.

It’s possible that Pew and other pollsters are making faulty assumptions about the nonwhite composition of the electorate, but that would be out of whack with the historical trend. As Ron Brownstein pointed out several days ago, the white share of the electorate has steadily declined in every election since 1992, from 88 percent of all voters to 74 percent four years ago.

My guess is that this trend will continue. In Pennsylvania, the Romney campaign’s hopes are probably an exercise in futility: According to the Real Clear Politics average, the last time Romney held a lead in the state was .... never. More broadly, on the national level, Obama will likely benefit from an electorate that is as diverse — if not a little more — than it was in 2008.

Jamelle Bouie is a staff writer at The American Prospect , where he writes a blog .