Donald Trump doesn’t like to be interrupted — by anyone.

So when Anderson Cooper started asking tough questions right from the beginning of Tuesday’s town hall event on CNN, the Republican presidential front-runner was immediately on the defensive — about his campaign manager, Corey Lewandowski, about protesters at his rallies and a whole host of other issues. And each time he and Cooper spoke over each other, Trump interjected, making sure to get his point across even when the CNN host was taking him to task.

“It’s the argument of a 5-year-old!” Cooper admonished him after he said Ted Cruz was responsible for starting the ugly and unpleasant exchange about the two candidates’ wives that dominated the news cycle last week.

“Excuse me. You would say that,” Trump responded. “That’s the problem with our country.”

Cooper continued to press him.

“Excuse me — no no, no,” Trump responded again.

By our count, Trump said “excuse me” 18 times over the course of the one-hour event.

Perhaps Trump is on the defensive because of the increased scrutiny on his campaign this week; between the controversy with Cruz and the separate controversy with Lewandowski, it hasn’t been the smoothest week of his candidacy. And maybe Cooper felt pressure to push Trump harder on questions — it was just a few days ago that New York Times columnist Nick Kristof accused the media of being too soft on him.

Either way, Trump isn’t likely to stop saying “excuse me” any time soon. There’s a long way to go between now and November, and that means more debates, more town halls, more protesters at rallies, a lot more tough questions to answer — and a lot of interruptions to head off.