In the ongoing effort to explain Scott Brown’s Senate victory in Massachusetts—a win that has not only thrown health care reform into disarray, but now seems to be shaping Barack Obama’s broader political strategy—a new contender has emerged: it was all about the “Cornhusker kickback.”

That phrase refers to the unseemly bit of sausage-making in which Democratic leaders persuaded Ben Nelson, the conservative Democrat from Nebraska, to support the health care bill in exchange for some special favors for his home state. According to a David Herszenhorn “Prescriptions” piece in Tuesday’s New York Times:

More than anything else, a paragraph on Page 2,129 of the Senate health care bill may be the primary reason Mr. Obama is now fighting for the survival of his top domestic priority.

Widely derided as the “Cornhusker kickback,” it called for the federal government to pay the full cost of a planned Medicaid expansion for Nebraska while other states would eventually pay a small part of the expense…

The public simply could not swallow the idea of Nebraska’s getting a free ride at the expense of 49 other states. The House speaker, Nancy Pelosi, singled out the provision on Thursday as a reason rank-and-file House Democrats would not just approve the Senate bill and send it to Mr. Obama.

Herszenhorn is reporting from D.C., which may limit his ability to know first-hand what the public could or couldn’t swallow. But the claim that Bay State voters had the Cornhusker kickback in mind was also made Sunday by Time’s Karen Tumulty, who was in Massachusetts to cover the election. Riffing off The Washington Post’s write-up of a post-election survey indicating that Brown voters had “concerns about the process,” Tumulty wrote:

The deal now known as the “Cornhusker Kickback” may have been one of the biggest blunders in modern political history. Normally, you’d be surprised if people in Massachusetts even know who the Senator from Nebraska is. But the number of people I talked to who brought up Ben Nelson’s name, unprompted, was striking. I’m also told, by some who were doing phonebanking, that they got an earful about it over and over.

This looks pretty solid: good, old-fashioned political reporting that’s based on talking to voters and asking what’s on their minds. The problem, as other commentators have noted over the past few days, is that this sort of shoe-leather reporting may presume an outdated model of voter decision-making.

Much political journalism assumes that voters approach a campaign with a set of concerns they want to see addressed. Over the course of a campaign, they follow the news so they can weigh the candidates’ platforms and their performance on the stump against those concerns. And at the end of the campaign, if you stop a voter on the street, or in a barbershop, and ask why he made the choice he did, he’ll be able to tell you.

But we have reasons to be skeptical that this is actually how voters get information and make decisions. People’s views on political issues are influenced by the messages they absorb from elite opinion-makers, who are increasingly polarized and have an increasingly national reach. And voters’ ability to identify the factors that shaped their choices is limited.

Greg Marx is a CJR staff writer. Follow him on Twitter @gregamarx.