Political campaigns now raise vast sums of money, and much of it goes to support a sprawling communications machine. It remains unclear, however, which types of campaign messages actually change voter behavior.
A new study from Wharton provides a clear answer: Speeches that fire up loyal supporters — the base — can turn off undecided voters when the media gives them wide attention.
“Any time there’s political messaging, when you try to appeal to one group you may end up alienating another,” said Wharton marketing professor Pinar Yildirim, who carried out the study with Camilo García-Jimeno, senior economist at the Federal Reserve Bank of Chicago and former Penn professor.
In their working paper “Persuasion and Dissuasion in Political Campaigns,” Yildirim and García-Jimeno analyzed more than 400 U.S. Senate races from 1980 to 2012, drawing on over 200,000 newspaper articles from a period before social media became a major force in political campaigns.
The results show that political campaigns often come across as polarizing because the media puts out the most divisive statements, as they tend to draw attention. Candidates know this and would prefer those messages not be amplified.
“Any time there’s political messaging, when you try to appeal to one group you may end up alienating another.”— Pinar Yildirim
How Politicians Lose Control of the Message
The paper draws a distinction between two types of voters. The first are loyal supporters who are unlikely to be swayed by any messaging; the second are those who are more centrist and could be nudged either way. Savvy politicians tailor their language to target these groups, often making more partisan speeches in front of their core supporters and being more cautious in front of centrists.
According to the study’s estimates, Democratic campaigns rely on base-focused appeals more often than Republicans, about 56% of the time compared with 45%. But while speeches that seek to fire up the base can boost voter turnout, they risk alienating swing voters once those speeches are amplified in the media. By contrast, messages aimed at undecided voters tend to be safer, but they do little to rally the base.
Yildirim said that the problem for candidates is they cannot control how their speeches are reported, owing to a free press. The study finds that the media tends to report speech aimed specifically at loyal supporters over more cautious statements. Those are more valuable to media outlets because they draw more attention.
As a result, candidates often lose control over which messages are amplified. A speech meant to galvanize loyal supporters may end up being front-page news, where it reaches swing voters instead.
“That is where backlash enters the picture,” said Yildirim. “Politicians almost have to play this game: They make attention-grabbing statements to appeal to their core supporters, knowing those messages may also reach voters they were not meant for.”
“Once you factor in media coverage, campaign behavior that looks puzzling starts to make sense.”— Pinar Yildirim
How Voters Respond to Democrats vs. Republicans
How those messages are received by voters differs depending on which side of the political aisle candidates sit on. The paper showed that Democrats gain more from rousing their staunch supporters than Republicans do, because their supporters are more likely to turn out and vote when called upon.
The study data bears this out: a 10% increase in core-voter messaging yields a 3.3 point increase in vote share for Democrats. For Republicans the same tactic boosts support by only 0.8 points. That is a significant gap in Senate races, which the authors note are usually decided by around five points.
However, the picture is more complicated than that. When partisan speeches from Democratic politicians receive wide media coverage, swing voters punish them more harshly than they do Republicans.
By contrast, Republicans gain less from rallying their base, since their supporters already turn out and vote at higher rates. But swing voters punish them less severely when they make partisan speeches that are picked up by the press.
In the end, the study’s authors say that these forces balance each other out, with both Democratic and Republican campaigns receiving media coverage at roughly the same rates.
The takeaway is ultimately that successful political communication comes down to not only persuading voters but also controlling what gets attention. The research shows that election outcomes depend not only on what politicians say, but also on which messages the media choose to run.
“Once you factor in media coverage, campaign behavior that looks puzzling starts to make sense,” Yildirim said.
