That’s why it is crucial campaigns and independent groups test their messages, create compelling ads that are easy to understand and that resonate at an emotional level, fully fund said ads, and then commit to running them in a concerned manner. I can’t be sure that I know what would persuade Republican primary voters to abandon Trump (that’s why you have to test messages), but I am curious what would happen if someone spent a million dollars, say, on an emotionally compelling ad about how Donald Trump cut off medical care to a sick infant—just to get back at his parents. Maybe that would resonate with voters. Who knows?

You don’t necessarily even have to tug at voters’ heartstrings. Some empirical evidence suggests that spending money on ads could have hurt Trump, even if the ads were solely based on economic policy.

According to RealClearPolitics’ polling average of Iowa, Trump peaked on Sept. 21 at 28.3 percent, and then began a decline (down to 22.3 percent) into second place by Oct. 6. Since then, however, Trump has rebounded in the state.

So what happened to cause Trump’s numbers to fall of a cliff in Iowa during that time? Here’s what: The conservative Club for Growth ran ads hitting Trump for his liberal positions.

That ad buy ran from Sept. 15th to Oct. 5th. So the date of Trump’s polling nadir in the Hawkeye State correlated precisely with the end of the Club’s $1 million ad campaign against him.