What if Obama had lied about his opposition to the Iraq war?

NBC News got an earful from critics after Matt Lauer on Wednesday night allowed Donald Trump to lie about opposing the Iraq war. The network got another, smaller earful from critics Thursday, when it posted this tweet.

Of course, there’s nothing “disputed” about it. His claim to have opposed the Iraq war before it began is false. As of Friday morning, the linked article portrayed the situation accurately, which suggests an upside to all of this weeks failures: Trump won’t be able to lie so brazenly about this to reporters and moderators in the future.

But what about the past? The fact that he’s gotten so far in this campaign on the basis of fabricated opposition to the Iraq war is genuinely shocking. It isn’t one of his more incidental lies, like that he’s a generous altruist or that Trump Tower sells the world’s best taco bowl. It rests at the foundation of the story he tells about his candidacy: that though he lacks governing experience, he has better judgment than both the 16 Republicans he defeated in the primary and “trigger happy” Hillary Clinton. Along with racism, it’s one of the big reasons he’s the GOP nominee, and it’s a story he continues to tell to this day about why he deserves to be president.

We don’t have to go back all that far to remember someone who, despite very little political experience, became president because he opposed the Iraq war when everyone else was falling into line. Now imagine it had been revealed in 2008 that Barack Obama’s opposition to the Iraq war was fabricated—that he’d just made it up. It wouldn’t have been “disputed.” He just would’ve lost. In other words, it isn’t good enough to simply correct Trump every time he repeats this lie going forward. It should dog him every day from now until the election, even if he stops telling it.