Donald Trump did a rare about-face Thursday, deleting a tweet he retweeted that suggested that genetically modified corn crops were creating "issues in the brain" for Iowa voters. A "young intern," he said, was to blame and "apologizes."

The original tweet, from Twitter user @mygreenhippo, alluded to a newly released Quinnipiac University poll that showed Trump in second place to retired neurosurgeon Ben Carson in the Hawkeye state. The poll showed Carson with 28%, compared to 20% for Trump.

Trump changed course, saying that the intern "apologizes," which is about as close as Trump gets to apologizing himself.

The young intern who accidentally did a Retweet apologizes. — Donald J. Trump (@realDonaldTrump) October 22, 2015

Taking swipes at the Hawkeye State’s voters is a sure-fire way to get the wrong kind of attention. Earlier this campaign cycle, a longtime Republican operative infuriated party officials with a series of tweets mocking the state’s caucus and its voters.

Jeb Bush’s chief strategist David Kochel characterized Trump as thin-skinned for his response.