To understand this, you need to read this quote from his new interview with Time first:

Well, I’m running it differently than I did the primaries. I am listening to so-called experts to ease up the rhetoric, and so far, I’m liking the way I ran in the primaries better. I got more votes than anybody in the history of the primaries, I got 14 million votes and won most of the states. But I’m now listening to people that are telling me to be easier, to be nicer, be softer. That’s OK, and I’m doing that. Personally, I don’t know if that’s what the country wants.

“Obama founded ISIS” is a money applause line in a GOP primary. And there’s truth to the underlying point: By pulling American troops out of Iraq to keep his campaign promise before the 2012 election, Obama left a power vacuum that made it easy for ISIS to grow and thrive. Conservatives have been criticizing him for that for years. Liberals have made the same point about George W. Bush, noting that Al Qaeda in Iraq would never have existed if not for his decision to invade and depose Saddam. Barack Obama himself once made that point. The difference between O and Trump is that Obama called the rise of AQI under Bush an “unintended consequence” of the war. Trump’s insistence on the word “founded” implies intent, at least if you’re a casual listener who isn’t already familiar with the conservative critique of O’s withdrawal policy. That’s not a misstep if your audience is a Republican electorate filled with voters who loathe Obama. Some might blanch at it but others will applaud you for being “politically incorrect” and willing to “take the fight to the left.” If your audience is the wider electorate, filled with Berniebros you’re trying to win plus millions of centrists who are open to voting for Trump but worry that he’s a loose cannon, “Trump says Obama founded ISIS” is a dumb, dumb headline to hand the media. Especially with O’s job approval higher lately than it’s been in years.

Hugh Hewitt tried to coax Trump off this ledge in a follow-up interview this morning. No dice.

HH: I’ve got two more questions. Last night, you said the President was the founder of ISIS. I know what you meant. You meant that he created the vacuum, he lost the peace.

DT: No, I meant he’s the founder of ISIS. I do. He was the most valuable player. I give him the most valuable player award. I give her, too, by the way, Hillary Clinton.

HH: But he’s not sympathetic to them. He hates them. He’s trying to kill them.

DT: I don’t care. He was the founder. His, the way he got out of Iraq was that that was the founding of ISIS, okay?

HH: Well, that, you know, I have a saying, Donald Trump, the pneumonic device I use is Every Liberal Really Seems So, So Sad. E is for Egypt, L is for Libya, S is for Syria, R is for Russia reset. They screwed everything up. You don’t get any argument from me. But by using the term founder, they’re hitting with you on this again. Mistake?

DT: No, it’s no mistake. Everyone’s liking it. I think they’re liking it.

It’s true, pretty much everyone is liking it — on the right, among people who are already locked in for Trump. Among the other 65 percent of the electorate, I guess we’ll find out. This is a recurring problem for Trump, seen most recently in what he said about “Second Amendment people”: He doesn’t seem capable of imagining how the things he says will be understood beyond his own fan base. Tom Joscelyn noted this morning that “Obama founded ISIS” is also an idea pushed by Iran’s supreme leader, Khamenei. He has a different meaning of “founded” than Trump does: He wants Shiites, who loathe ISIS, to believe that the organization was deliberately created and equipped by the U.S. to persecute them. That’s not what Trump means by it, but because he insists on using a word that implies intent in describing Obama’s role, Iran can use the clip of Trump in its English-language propaganda. Trump either doesn’t grasp that or doesn’t care enough to be more precise with his criticism.

Meanwhile, here at home, imagine a casual voter loading a news site today and seeing a headline about Trump accusing Obama of founding ISIS. Odds are the casual voter doesn’t know much about ISIS’s origins and will miss Trump’s point about Obama’s negligence in withdrawing American troops. What he might know is that Trump was the most famous Birther in America a few years ago. He might also have noticed back in June that Trump seemed to go out of his way in interviews to suggest that Obama was sympathetic to Islamic terrorists, and that the reason for that might be secret. (“There’s something going on… He doesn’t get it or he gets it better than anybody understands.”) Imagine being a Bernie Sanders supporter or a center-left independent — two groups being wooed by Trump — who’s well disposed towards O and seeing stories about today’s “Obama founded ISIS” soundbite. What conclusion would you draw about Trump? He’s all but accused a president you admire of being a closet jihadi. You ready to vote for that guy over Clinton? In poll after poll, Clinton trounces Trump on questions related to presidential temperament. Would “Obama founded ISIS” give you, the hypothetical center-left swing voter, more confidence in Trump’s temperament? Or would it convince you that Trump is a demagogic crank?

One last point. It’s passing strange that Trump, who’s strained so hard to convince voters that he was against the Iraq war from the beginning (not true but a smart strategy), would turn around and start attacking Obama for not leaving American troops in the field beyond 2011. Those two positions aren’t mutually exclusive — you can believe that the war was a bad idea but also that the peace had to be kept once the U.S. was there — but it does muddy his message that he never wanted Americans there to begin with. What would really undercut his point is if it could be shown that Trump supported withdrawal after the war had already raged on for several years, with Iraq in chaos. And lo and behold, look what CNN found:

He wanted to get out at the very worst point of the war, when Bush was implementing the surge to try to create a buffer between Sunnis and Shiites. Without that, you might have had Iraq turn into Syria. Either Al Qaeda in Iraq would have grown as the prime defender of the Sunni territories against the Shiites or an ISIS-style group would have arisen to fill that void. If you’re serious about criticizing O for “founding” ISIS by undertaking a too-hasty withdrawal, you probably shouldn’t have called for an even hastier withdrawal yourself.

I’ll say this much for Trump, though: Liberal bloggers who criticize him for this had better be very sure they’re not throwing stones from the porch of a glass house. Some of them already are.