Republican presidential nominee Donald Trump speaks at the National Guard Association of the U.S. General Conference & Exhibition at the Baltimore Convention Center on Sept. 12. (Jim Lo Scalzo/European Pressphoto Agency)

The question of whether Donald Trump still supports a ban on Muslim immigrants and refugees coming to the United States just got a whole lot murkier.

The Republican presidential nominee has recently sought to emphasize the concept of "extreme vetting" -- apparently as an alternative to his previous blanket proposal to block all foreign Muslims from coming to the United States. But his comments Wednesday night in Canton, Ohio, suggest that even he doesn't think such vetting could work.

"We don't know where these people come from," he said while discussing Syrian refugees. "We don't know if they have love or hate in their heart, and there's no way to tell."

Trump's comment that "there's no way to tell" whether people have hate in their heart is completely at odds with his proposal to exhaustively vet immigrants. He said last month that the vetting would include an ideological screening test to determine whether people "share our values and respect our people."

In other words, the test is meant precisely to determine whether people have love or hate in their hearts.

Trump was talking specifically about Syrian refugees, who apparently still would be banned even under his revamped proposal. But he also is talking about a matter of the heart -- not documentation, which Syrian refugees may not have. And if you can't see what's in a Syrian refugee's heart, you also can't see what's in the heart of a Muslim immigrant from England. The latter might have more paperwork, but that's not what Trump is talking about here.

It's just the latest example of the candidate seeming to argue with himself about his proposed ban.

While adding the "extreme vetting" proposal, the Trump campaign has offered conflicting signals about just whom the vetting would cover and how much he's backing away from his previous proposal to ban all Muslims from coming to the United States. That proposal, by the way, still appears on the Trump campaign website under the headline: "Donald Trump Statement on Preventing Muslim Immigration."

In May, the candidate deflected questions about whether the Muslim ban was still his policy, saying, "We're going to look at a lot of things."

In June, Trump suggested that the ban would not be on Muslims but on countries "where there is a proven history of terrorism."

Later that month, Trump said it "wouldn't bother me" to admit a Muslim immigrant from Scotland. A spokeswoman at the time told CNN that his Muslim ban applied only to Muslims from "terror states," but didn't elaborate beyond that.

Trump then delivered his speech on extreme vetting in August.

Trump's comments Wednesday even contradict his own remarks from two weeks ago when Sean Hannity asked him specifically about vetting what's in one's heart and Trump suggested there was a way:

HANNITY: How do you possibly vet what's in their heart?

TRUMP: Right, let me just tell you, you get very smart people, and there are those people. And they are very good at understanding what's going on. But beyond that, you use social media, because a lot of these people, I mean, they are better at social media than we are. ISIS, if you look at what ISIS is doing with social, they are recruiting over the Internet. And I also said we have to end that.

Through it all, the Trump campaign hasn't clarified whether he is disowning his blanket ban on Muslim immigration, whether he is strengthening it, or whether he is scaling it back. He or his top aides and surrogates have indicated all of these things at one point or another. (The New York Times has a good visualization of how the proposal has shifted over time.)

Asked in July whether he was scaling back his proposal, Trump told NBC's Chuck Todd: "I don't think so. I actually don't think it's a rollback. In fact, you could say it's an expansion."

Trump's comments Wednesday night further obscure what his exact proposal on this is. In his Ohio speech, Trump repeated a previous comment that Syrian refugees could represent "the great Trojan horse."

"I don't want to be known in 200 years for having created the Trojan horse with a different name," he said.

Trump still doesn't appear to have decided precisely how he would halt that Trojan horse.