Donald Trump's supporters aren't fazed by his decision to cancel an appearance at a Chicago rally over the weekend—in fact, they are more likely to vote for him to be the Republican nominee because of it.

That's according to a new poll of likely Republican voters conducted by Monmouth University. It confirms something I've long suspected (and have argued in previous articles): the antics of left-wing agitators are driving ordinary people into the arms of Trump.

The poll noted that pro-Trump and anti-Trump forces clashed in Chicago last Friday, which prompted Trump to cancel the event. It then asked respondents whether this fact made them more or less likely to support Trump. Just 11 percent said they were less likely to support Trump because of this decision. Another 22 percent said they were actually more likely to back Trump, and 66 percent said their views were unchanged.

Leftist protesters who vehemently oppose Trump would do well to remember that in a free society, even contemptible speakers are permitted to be heard. As New York Magazine's Jonathan Chait wrote in a recent piece:

But the whole premise of democracy is that rules need to be applied in every case without regard to the merit of the underlying cause to which it is attached. If you defend the morality of a tactic against Trump, then you should be prepared to defend its morality against any candidate. Now imagine that right-wing protesters had set out to disrupt Barack Obama's speeches in 2008. If you're not okay with that scenario, you should not be okay with protesters doing it to Trump.

Indeed. But the Monmouth poll is good evidence that letting Trump speak is not merely the morally correct, philosophically consistent course of action: It's the tactically sound one as well. When the left stops Trump from speaking, Trump wins. He gets to tell his people that the forces of far-left activism and political correctness are trying to silence him. Implicitly, he is suggesting to his followers that when he becomes president, the tides will turn: see his promise to make it easier to sue newspapers for criticizing him. Trump supporters adore this shtick. Stop giving them ammunition.

Related: The Main Casualty of Canceled Trump Rally is the Idea of Free Speech