Adam B. Schaeffer, Ph.D., is co-founder and CSO of Evolving Strategies and ES Partners.

So far this campaign season, anti-Donald Trump forces have spent close to $70 million on ads attacking the GOP front-runner—more than triple what Trump has spent on his entire campaign. Even more shocking than the whopping amount of cash deployed against the mogul, though, is that the ads haven’t been working. In fact, they might even be helping Trump.

Polling data from states such as North Carolina, Florida and Wisconsin, show that anti-Trump ads did no damage to his support in those states, or nationally. And new evidence from a clinical message trial my firm conducted shows that the ads could actually be boosting it.


This could have a big effect on the rest of the GOP primary. Since Trump’s big loss in Wisconsin, the #NeverTrump contingent has been optimistic about stopping him at a contested convention. But that all depends on whether the anti-Trump forces that only recently massed against the front-runner can keep The Donald from winning the big states left in the contest—especially New York, Maryland, Indiana and California. For this, mass communication will be critical; no one can hope to sap Trump’s support without going big with effective attack ads.

And so far, the attack ads haven’t been so effective.

The Florida primary was the first big test of the anti-Trump onslaught. According to data from the Political TV Ad Archive, nearly 5,000 ads attacking Trump aired in Florida this season. The Marco Rubio-aligned Conservative Solutions PAC alone spent over $9.5 million on ads there. And the effort clearly failed—not because Trump won the state, but because there is no evidence the attack ads hurt Trump.

Over the past two weeks before the primary, the airwaves were flooded with anti-Trump ads. They attacked him on a wide range of fronts, including Trump’s conservative heresies, his business dealings and his outrageous and insulting statements. And yet as the ad war ramped up in the final week, Trump’s support stayed relatively steady in both Florida and national polls. Trump’s support even increased a bit in the last days before the primary.

The attack ads seem to have failed in other states as well. The Ted Cruz campaign blasted Trump in the last days of the North Carolina primary. An overlay of the polling and advertising trends suggests that, if anything, the attacks boosted the billionaire’s support. Of course, these are what we scientists call “observational” data; based on these, we can’t say the attacks caused Trump’s support to increase in North Carolina.

But we don’t have to rely just on the observational data in making our case. In mid-January, my firm Evolving Strategies conducted a clinical message trial in partnership with Qualtrics to measure the impact of an anti-Trump ad from the Cruz campaign. The attack ad we tested focused on Trump’s ideological heresies and “New York values.”

We recruited a nationally representative sample of self-identified Republican and Republican-leaning voters who supported a range of candidates to an online survey. Once in the survey, each respondent was randomly assigned to a treatment or placebo-control group, just like in a clinical drug trial. Respondents assigned to the placebo-control group watched a Coca-Cola ad, while those in one of the treatment groups watched a Cruz campaign ad attacking Trump for being an abortion rights supporter and having “New York values.” We asked each respondent, after watching the ads, whether they’d seen the ad as a way of distracting them from any indication that we wanted them to react to the ads in a particular way. We then asked voters who they would eliminate from the primary race if they could, and then asked for whom they would vote out of the remaining candidates.

The key distinction in what we do compared with focus groups and regular polls is that we do not ask what people think of a message; we observe the impact the message has on vote choice in the treatment group compared with the placebo-control group. Since the respondents are randomly assigned to each group, average support should be about the same in each. Any statistically significant difference between support in the two groups is because of the impact of the ad.

And we found that Cruz’s anti-Trump ad backfires. It doesn’t hurt Donald J. Trump. It helps him.

Our clinical message trial showed Cruz’s anti-Trump actually made voters more likely to vote for Trump, boosting his support by 3 percentage points overall. That’s not a very large increase for the sample as a whole (and not statistically significant). But for blue-collar voters, the attack ad increased support for Trump by 18 percentage points; and it increased support among blue-collar men by more than 33 percentage points. (36 percent of the blue-collar men who watched the coke ad, for example, said they would vote for Trump—compared with 69 percent of the blue collar men who watched the anti-Trump ad.) And in both subgroups, incidentally, the anti-Trump ad caused actually support for Ted Cruz to fall.

While the ad decreased support for Trump among other groups, such as middle-class voters overall, by a few points, that large backlash among blue-collar voters is significant. It is certainly not a result you want to see from broadcast ads that are viewed by a wide range of voters.

It’s no surprise, then, that we see the same pattern in Wisconsin that we saw in North Carolina. Cruz did outperform his projected margin, but we shouldn’t confuse winning with effective advertising.

The polling patterns over the last two weeks of the Wisconsin campaign again suggest that the ads there were at best ineffective and at worst counterproductive. During that time, support for Trump in Wisconsin rose about 34 percent from the high 20s to the high 30s—while Trump’s national support remained steady.

So, did the anti-Trump forces unintentionally boost support for their nemesis with these attack ads? It’s possible, perhaps even probable, given the evidence. You’d expect a candidate to lose at least a little support under that much fire. But the opposite happened. And our clinical trial results show that backlash to at least one attack ad is real and powerful.

The anti-Trump forces surely tested their ads with polls and focus groups. So how is it that they failed so thoroughly? It turns out you can't ask voters how they think an ad will affect them—you must observe the impact on voters. And there's only one way to do that: run a randomized-controlled trial like we did. Persuasion isn’t an art—it’s a science.

The real tale of Trump’s success is not that he couldn't be stopped, but that when the anti-Trump forces finally coalesced and made a go of it, they went in blind, with no scientific evidence of what worked and what backfired and whom to target. They likely ended up helping Trump rather than hurting him.

If the anti-Trump forces keep it up, they might just succeed in nominating Donald J. Trump.