In 2008, the Democratic polling firm Greenberg Quinlan Rosner described Macomb County, Michigan—home to the bellwether suburbs north of Detroit—as “90 percent white, half Catholic, 40 percent union families, one third over 60.” Macomb was once the most Democratic suburb in the country, giving LBJ 75 percent of the vote in 1964, but it swung sharply to Republicans in the 1980s and has been a pivotal swing county in the state ever since. Gore won it by two, Kerry lost it by one and Obama won it by eight.

The archetypal “Reagan Democrats” make up a fifth of Macomb’s electorate. These blue-collar, non–college-educated white voters abandoned the Democratic Party in the ’70s and ’80s, out of anger at Democratic support for policies like welfare and affirmative action, and leapt into the outstretched arms of Ronald Reagan, who won Macomb County by thirty-three points in 1984. They’ve been an important part of the GOP coalition ever since. “In the 2008 Michigan primary,” wrote National Journal’s Ron Brownstein, “57 percent of GOP voters lacked a college education and 75 percent earned less than $100,000 annually.”

It’s become conventional wisdom to suggest that Rick Santorum, with his blue-collar background in Pennsylvania, will run strongly among these voters. “He has a big appeal to people we used to call Reagan Democrats,” said former Ohio Senator Mike DeWine. A recent Gallup poll showed Santorum leading Mitt Romney by double digits among Republicans without a college degree and making less than $90,000. Romney’s unfavorable rating among voters making less than $50,000 jumped twenty points in January, which Greg Sargent termed “Romney’s White Working Class Problem.”

Yet these national poll numbers haven’t translated to an advantage for Santorum in Michigan or the other states that have voted so far (there’s no exit poll data for Colorado, Minnesota and Missouri, where Santorum won). “Santorum’s performance doesn’t show much more variation by income,” notes Brownstein. “In Iowa, his share of the vote rose steadily with income.”

Romney narrowly leads Santorum in the latest Michigan polling. In an NBC/Marist poll, they are tied among voters making less than $75,000, but Romney is up five among voters making more. Romney leads by two among those without a college degree and by one among those who’ve graduated college. “There’s lots of evidence that Reagan Democrats have pulled back from Romney,” says Democratic pollster Stan Greenberg, who has studied this group of voters for three decades. “But we don’t know yet whether they’ll embrace Santorum. They do not really know him, though conservative pundits think he will have more of a working class appeal than Romney. Could be true—but only because Romney went Wall Street.”

Nor will Santorum’s outspoken social conservatism necessarily help him win Reagan Democrats. “I don’t think they are particularly socially conservative, if you are referring to abortion and family issues raised by Santorum,” Greenberg says. “They are fairly libertarian and anti-government intrusiveness—and are much more concerned with guns than the pill. They were/are strongly NRA in our research.” In 2008, Romney won Macomb County with 45 percent of the vote, while evangelical favorite Mike Huckabee came in a distant third.

No matter who wins the Michigan primary on Tuesday, the GOP nominee is likely to lose the state in the fall to Obama. Obama leads Romney by eighteen points in the latest NBC/Marist poll and Santorum by twenty-six. He also leads Romney by twenty points in Macomb and neighboring Oakland County (which is more upscale) and Santorum by twenty-two. Obama now has a 51 percent approval rating in the state. Fifty-five percent of Michiganders say the worst of the economic crisis is behind them, while 63 percent believe the auto bailout—which Obama supported and Romney/Santorum did not—was a good idea (GOP primary voters narrowly oppose it).

Obama’s numbers among working-class whites help explain why his re-election prospects are improving. In 2008, Obama lost the white working-class vote by eighteen points. Democrats lost that group by thirty points in 2010, which many pundits predicted would be replicated in 2012. “Preparations by Democratic operatives for the 2012 election make it clear for the first time that the party will explicitly abandon the white working class,” Tom Edsall wrote in November 2011.

Edsall’s prediction generated a lot of buzz, but turned out not to be true. Obama has a 43 percent approval rating among working class whites in the latest Washington Post/ABC News poll, higher than it was in 2008. At the beginning of 2011, Romney led Obama by around twenty points among blue-collar whites in Indiana, Michigan, Ohio and Wisconsin, according to internal polling by Greenberg Quinlan Rosner. At the end of last month, Romney led the president by only three among such voters in these Rust Belt battleground states, a seventeen-point swing over the past year. “White non-college voters in these states moved drastically away from Obama and Democrats between 2008 and 2010, but since then they have come back to basically the same levels they gave Democrats in 2008,” says GQR vice president Andrew Bauman. 

Ari Berman is the author of Herding Donkeys: The Fight to Rebuild the Democratic Party and Reshape American Politics, out now in paperback.