Former Massachusetts governor Mitt Romney has struggled consistently with low-income voters.

But the takeaway from Michigan might be less that Romney has trouble with the working class than that he has a particular hold on the wealthy.

A supporter's reflection and the image of Republican presidential candidate, former Massachusetts governor Mitt Romney, are seen on the screen of his iPad as he photographs Romney, greeting supporters at American Posts in Toledo, Ohio, Wednesday, Feb. 29, 2012. (Gerald Herbert/Associated Press)

Lower-income voters have a more volatile reaction to the candidate: Sometimes they support him, sometimes they don’t.

Republican strategist Mike Murphy, who worked on Romney’s 2002 gubernatorial campaign, argued that Romney’s trouble with lower-income voters can be traced to their social conservatism, not the candidate’s wealth.

“I think there is a media narrative where everything he does is under an electron microscope of class,” said Murphy. “But the media buys the old lefty frame that working-class voters don’t vote for rich guys.”

At least for Republicans, Romney’s actual wealth does not appear to be a factor.

Among the overall public, only 38 percent of those making less than $100,000 see Romney’s wealth as a positive compared with 65 percent of those making over $100,000, according to a February Post-ABC News poll.

But among Republican voters, there’s little difference based on income — six in 10 see his wealth as a good thing.

The social issues question is more difficult.

Post polling from late 2010 finds that lower-income voters (across party lines) are less likely to support abortion and gay marriage.

In Michigan exit polls, higher-income voters were more likely to say abortion should remain legal and less likely to be born-again Christians.

But according to statistician Andrew Gelman, who studies voting patterns and income, while rich people tend to be more liberal on social issues (here’s a chart that goes into more detail), they are also more likely to vote on those issues than the less well-off.

“Social issues are a more important factor for richer people than poorer people,” he said. “Higher income people have the luxury of voting on social issues.”

Very few voters this cycle have identified “values” as their driving concern; the economy dominates. Romney won “somewhat conservative” voters in Michigan by a higher margin than former Pennsylvania senator Rick Santorum won “very conservative” voters.

The most salient difference between high-income and low-income voters in this primary, then, might not be social issues but divergent opinions on electability.

High-income voters were far more likely to see Romney as the most electable candidate than voters who made less than $100,000 a year and to prize electability above all else.

Romney’s wealth-related gaffes might be a factor here, irritating lower-income voters more than their more comfortable fellow Republicans.

“People are like, ‘Yeah, he’s probably going to win, but I really don’t like him, and I’m not going to vote for him,’” one high-ranking Ohio Republican told Amy Gardner. “That’s the collective zeitgeist.”

Former House speaker Newt Gingrich’s super PAC allies are already exploiting that idea. In a new ad, voters express a vague distrust of Romney. As one says, he’s “not the type to pump his own gas.”

With Peyton Craighill