Democratic presidential hopeful Bernie Sanders speaks at the Phoenix Convention Center in Phoenix on July 18, 2015. (Patrick Breen/Arizona Republic via Associated Press)

Before the Iowa Democratic caucuses, Bernie Sanders announced, “We will win tonight if turnout is high. We will struggle tonight if the turnout is low.” Although the turnout was high by historical standards, it fell short of the approximately 200,000 Iowa Democrats that many thought were necessary for Sanders to win. It also fell short of the turnout in 2008.

One reason was lower turnout among new voters, especially young voters. Overall, 30,800 young voters (ages 17 to 29) turned out for the Democratic caucuses, making up 18 percent of all Democratic caucus-goers. This was lower in both absolute and relative terms than in 2008, when 52,580 young Democrats turned out and made up 22 percent of the electorate. And, overall, first-time caucus-goers made up only 40 percent of caucus-goers this time as compared with 57 percent in 2008.

Although there are many differences between 2008 and 2016, and although Sanders clearly finished ahead of what many expected as recently as a few months ago, it remains the case that many of the new caucus-goers he was hoping for did not materialize.

Why might that be? A lot of attention has been focused on the demographics – how difficult it is to get young people to turn out in general – but we also need to think about Sanders’s campaign message.

A lot of his rhetoric reminds people about their poor financial situation. While attacking Wall Street and big money in American politics, he often dwells on Americans’ experiences with financial insecurity, including skyrocketing college loans, the lack of decent-paying jobs, stagnant wages, the cost of health care and so on. These experiences have affected all kinds of Americans, and especially the new, young voters  Sanders is trying to appeal to.

Carrie Aldrich wasn't sure if she should speak up. But when Bernie Sanders asked for stories about living on low wages, she felt compelled to take the microphone. (Dalton Bennett/The Washington Post)

In my research I find that rhetoric about economic insecurity — such as job loss, health-care costs, college costs and so on — often has an unexpected effect: It demobilizes people, rather than spurring them to action.

The reason is simple: People don’t want to spend time and money on politics, even on issues that are important to them, when they’ve just been reminded about how poor they are.

This kind of rhetoric from candidates can lead people to support them. But expressing support in a survey is not the same as taking action on their behalf — such as spending a couple of hours at a caucus meeting on a chilly February night. Even spending time caucusing is arguably viewed as a much bigger time commitment than a relatively quick trip to the polls to vote in a primary.

On the face of it, Sanders’s success raising campaign money would seem to contradict this argument. After all, he has amassed donations from more than 3.5 million individual contributors, the large majority of which are less than $200.

Why has he been so successful at raising money? Based on the Sanders email solicitations I’ve seen, as well as the information on his website, Sanders’s fundraising appeals make a subtle, but significant, shift in rhetoric.

The major reason Sanders is asking people to donate is not because they are facing financial insecurity and he has proposed initiatives to help them. Rather, it’s because he’s not getting his money from anywhere else.

His fundraising appeals remind potential supporters that he isn’t relying on super PACs and that a donation to him is “building a movement” that will “take back our country from the billionaire class.”

In short, Sanders is discussing two related, but separate, things: skyrocketing income (and associated campaign donations) among the wealthy, and heightened economic insecurity in the broad middle class.

Focusing on the former fires up a lot of people. Focusing on the latter might fire a lot of people up, but it probably won’t make them spend money or time.

Adam Seth Levine is an assistant professor in the Department of Government at Cornell University.