In fall 2006, before Barack Obama and his coterie of astute political strategists decided to launch his campaign for president, they burrowed into the polling details of the U.S. Senate race in Tennessee that year.

Why? That was the most recent contest in which race might have played a significant factor in the outcome of a statewide election. Democrat Harold Ford, an African-American Congressman, narrowly lost the Senate race to Bob Corker, a white Republican.

That razor-thin loss by a black candidate—in a Southern state of all places—signaled to the Obama brain trust that the racial divide in America might be closing enough that a black candidate with crossover appeal such as Obama could generate enough white votes in a presidential contest to pull off victory. So Ford’s near success heavily contributed to Obama launching his historic bid a few months later.

But coming down the home stretch in this presidential race, those hopes are being tested, as Obama’s team watches its candidate struggle to hold onto slim leads or fall behind in key Midwestern battleground states—despite political dynamics that seemingly would put Obama suitably ahead. Polling averages by RealClearPolitics show Obama clinging to narrow leads in Michigan and Pennsylvania, while struggling to gain traction in Ohio, Indiana, and Missouri. Minnesota is a toss-up, while Wisconsin, once solidly in Obama’s favor, has edged toward a being an actual contest come November 4th.

Some white voters in these states consistently tell pollsters that they are voting Democratic straight up the ticket, until they reach Obama—and with him, well, they’re not sure.

In Ohio in recent years, voters unhappy with Republicans dominating state politics elected a Democratic governor and tossed its legislature back into the hands of Democrats. Stridently liberal Democrat Sherrod Brown ousted Republican incumbent Mike DeWine to claim a U.S. Senate seat in 2006. It would seem that the Buckeye State is ripe for the Democrats, yet polls show a small lead for John McCain.

Why is the Midwest such a difficult nut to crack for Obama? It’s impossible to overlook how race might contribute to his struggles here. Researchers studying data from the 2000 U.S. Census found that the Midwest more stubbornly clings to racially segregated housing patterns than other parts of the country. Cities like Detroit, Milwaukee, Cincinnati, St. Louis, Indianapolis, and, yes, Chicago, are among the country’s most pronounced segregated regions for blacks and whites.

While the rapidly growing South and West have grown more integrated, as blacks have returned to the South in large numbers and the West has rapidly expanded population, the Midwest hasn’t seen these major shifts. Housing lines in the Midwest were drawn generations ago, and so blacks and whites still largely live in separate communities throughout Ohio, Michigan, Missouri, Indiana, Missouri, and western Pennsylvania. Thus, it’s not surprising that my hometown of Cincinnati was the site of a race riot as recently as 2001.

Overall, Obama’s minority status has certainly abetted his political career. His rise to stardom is at least partially tied to his unique biography and racially mixed persona. His message of unity and harmony among political partisans and between the races has won converts from various demographic groups, especially the young. But throughout his presidential quest, Obama has struggled to win over older, white, working-class voters. I can’t help but think it’s because some of these folks are having problems processing the prospect of a president like Obama—a black man who graduated from Harvard Law and is lost on the bowling alley. He’s dramatically unlike anyone they’ve encountered in their daily lives.

In Obama’s Senate race in 2004, it was fascinating to watch him woo white Democratic crowds throughout the state: on college campuses, in small towns, and across the Chicago region. But during a campaign day at the Illinois State Fair that year, Obama struggled to gain even the modest attention of a nearly all-white, male-dominated, non-partisan audience—a lunch crowd that had not been prearranged as a political meeting. As Obama grabbed a microphone and delivered remarks about the significance of a proper education, religious faith, and personal responsibility, audience members initially stared at him with puzzled looks. Most eventually went back to chewing on steak sandwiches and sipping beer.

Obama certainly has the attention of that sort of white working-class crowd these days. But whether enough of them here in the Midwest will vote for him could determine whether he reaches the White House.