Much of the mainstream media have had to face the inconvenient news today that, yep, Donald Trump’s racist birther beliefs are alive and well. Inconvenient because, although the MSM has given Trump’s presidential campaign extraordinary amounts of coverage, they’ve largely forgotten—willfully or not—that in his view Barack Obama is some kind of Kenyan-born Muslim. “Oh, that birther thing—that’s old news,” they figure. “We can’t take our eyes off the new, winner Trump.”

But thanks, benighted guy, whoever you are, for bringing Donald’s recent past up to date, by asking at a town-hall meeting last night: “We have a problem in this country, it’s called Muslims. We know our current president is one. You know, he’s not even an American. Birth certificate, man.”

“Right,” Trump mumbled, then went for a laugh: “We need this question? This first question?”

“But anyway,” the man added, “we have training camps… where they want to kill us.”

“Uh huh,” Trump said.

“That’s my question: When can we get rid of them?” the man said.

Trump never corrected the guy by stating that president is an American and a Christian. But he did go on to throw it all into a pot of “things” said by “a lot of people.” “We’re going to be looking at a lot of different things, a lot of people are saying bad things are happening. We’re going to be looking at that and plenty of other things.” Watch him here:

OK, give him a huge benefit of the doubt: Maybe he didn’t quite understand or hear the question. But then a second man rose up and said, “I applaud the gentleman who stood and said Obama is a Muslim born abroad and about the military camps, everyone knows that.”

“Right,” Trump said, and then moved to another questioner.

As social media went nuts, the Trump campaign responded with a cowardly dodge: “The media wants to make this issue about Obama. The bigger issue is that Obama is waging war against Christians in this country. Their religious liberty is at stake.”

Today the corporate media are finally covering Trump’s lies, with Fox News predictably defending their brother in birtherism. On Stuart Varney’s show this morning, radio host Tammy Bruce said no Republican is obliged to defend Barack Obama, and “I wouldn’t be surprised if this was a plant.”

Until last night, Trump has successfully built a great big wall to keep his ugly birther narrative from crossing into his current presidential run. His candidacy now turns on his racist immigrant-bashing. It’s not that the press has completely forgotten the birther storm, which peaked in 2011; they have brought it up occasionally since he began running this summer. But, led down various rabbit holes by the accomplished deal-maker, they only push so far.

In a Meet the Press interview last month, for instance, Chuck Todd asked Trump if he still believes Obama faked his birth certificate.“Well, I don’t like talking about it anymore. Because, honestly, I have my own feelings,” Trump said—and then smoothly diverted Todd with less damning malarkey about Obama’s college transcripts.

Anyway, much of the media figures, with Trump there’s so much to cover—his daily stunts, his insults, his beguiling evasiveness—in fact, it’s hard for TV pundits to talk about him without smiling a bit, impressed by how he slips out of our hands—to harp on birtherism would communicate that we’re stuck in the past. It’s not news. After all, if the man who can’t keep his mouth shut no longer barks about birth certificates, it might be because he doesn’t believe it anymore, right?

But it should be news. And if it hasn’t “been a focal point for Beltway reporters and pundits,” it’s because it goes much deeper than they’re ready to acknowledge, Eric Boehlert wrote at Media Matters even before Trump’s birther fetish came back to bite him last night:

What’s truly bewildering and newsworthy is that the birther ranks are apparently expanding and likely number in the millions nationwide. The fact that Republican frontrunner Donald Trump personally vouched for the baseless, anti-Obama conspiracy theory has only elevated its significance….

The media’s birther blind spot is part of the larger press failure to grasp, and accurately detail, the truly radical nature of the Republican Party under President Obama.

For instance, since June 1, the New York Times has published approximately 180 articles or columns that included the word “Trump” five or more times, according to Nexis. But just a handful of those have made any mention of Trump’s previous birth certificate folly. The same goes for USA Today and the Los Angeles Times, for example: Nearly 180 detailed Trump articles and columns published since June between them, but just a few that have addressed the birther nonsense.

I’m not suggesting the topic has been completely ignored. But it is safe to say it’s not a priority issue for the press, which seems otherwise consumed with all things Trump.

Boehlert goes on to cite polls attesting to the size of the birther vote. According to a Public Policy poll earlier this month, “66% of Trump’s supporters believe that Obama is a Muslim to just 12% that grant he’s a Christian. 61% think Obama was not born in the United States to only 21% who accept that he was.”

And all that is of a piece with Trump’s demagoguery on deportations and “anchor babies.” The poll adds that “63% want to amend the Constitution to eliminate birthright citizenship, to only 20% who want to keep things the way they are.”

To be fair, avoidance of the B-issue isn’t solely due to the media taking the easy way out. The belief that Trump moved past his birther fixation after President Obama slaughtered him at the 2011 White House Correspondents’ Dinner is a powerful one. Even the estimable Charles Pierce said, on All In with Chris Hayes, that the reemergence of the issue last night had caught him off guard—he thought that the WHCD had “wrung” the birtherism out of Trump.

If you recall, Obama had just released the “long form” birth cer­ti­fic­ate, which took the air out of whatever it was that Trump’s “team of investigators” were supposedly digging up in Hawaii. As Obama told a worldwide audience, with Trump sitting in the audience, cameras trained on his frozen face:

And then there’s a vicious rumor floating around that I think could really hurt Mitt Romney. I heard he passed universal health care when he was governor of Massachusetts. (Laughter.) Someone should get to the bottom of that.

And I know just the guy to do it—Donald Trump is here tonight! (Laughter and applause.) Now, I know that he’s taken some flak lately, but no one is happier, no one is prouder to put this birth certificate matter to rest than the Donald. (Laughter.) And that’s because he can finally get back to focusing on the issues that matter—like, did we fake the moon landing? (Laughter.) What really happened in Roswell? (Laughter.) And where are Biggie and Tupac? (Laughter and applause.)

Surely, being laughed at in front of millions (8 million-plus hits on this video alone, but Donald’s face more visible here) might disabuse him of his lie, or at least persuade him not to mention it again, ever. No one—before or after that—has humiliated Trump as exquisitely, and in a way that left him unable to respond with the sort of “whatevers” that serve him so well now. (S.V. Date wrote in National Journal just days before the latest brouhaha, “If Republicans want to know how to get under the GOP front-runner’s skin, they should follow the example set by” Obama, the “Trump-Troller in Chief.”)

Here’s a theory: The real reason Trump decided to run for president this time—after so many false starts—is to avenge himself. To make the world forget that moment.

After all, as he constantly warns, he never backs down and he always counterpunches. Even if to do so, he has to wait a few years and take the Republican Party down with him.