"Anderson, they changed the rules a number of months ago," Trump replied.
"About eight months ago," Cooper replied.
"Well, that's not very long ago!" Trump countered.
Just to draw a line through this, Trump is saying that eight months is not enough time for his team to have gotten up to speed on rule changes delineating how the nomination process works.
Let's now jump forward a bit in the conversation, to the point at which Ivanka, Trump's daughter, is responding to having failed to register as a Republican in time to vote for her father in next week's New York primary.
"I'm an independent and I've always voted based on the candidate as opposed to based on the party," Ivanka said. "We're not a family of politicians. We haven't been in politics very long. New York has one of the most onerous rules in terms of registration, and it required us to register a long time ago, almost -- close to a year ago. And we ... we didn't do that."
The "year ago" line was used by Trump when the topic was first broached earlier this week. But the rules don't mandate registering a year in advance. The deadline was actually in October, about six months ago.
Which, per Donald Trump, is not very long ago at all -- when he wants it not to be.
Trump is right when he says that the way the process is set up to reward candidates embraced by the Republican Party. There's not much of a secret to this; there was a book called "The Party Decides," which details how the party establishment has guided eventual nominee picks.
That's different than saying the party is cheating. Priebus is right that the rules were set well in advance, and critics of Trump are right in saying he simply got outworked by Cruz's campaign in Colorado. As was the case after he did surprisingly poorly in Iowa, Trump is blaming others for his campaign's failure to do much more than hold rallies and cross their fingers.
The nomination process is less NASCAR's Sprint Cup than it is a decathlon. Trump did well at the 100 meters and the 400 meters -- the straight-up votes-lead-to-delegates contests. But in the long jump and the high jump contests, different sorts of competition, he's getting beaten. He got beat in Colorado and he's losing fights over unbound delegates in other places. Trump's argument, in essence, is that he also ran very quickly down the runway toward the long jump and that's what should count. But that's not how a decathlon works.
His excuses to Anderson Cooper make that obvious. The rules were changed practically yesterday when he needs to demonstrate that he couldn't possibly have been prepared for them. The deadline was so long ago when he needs to explain away his family's failure to get geared up for the campaign.
A better and likely more accurate explanation derives from Ivanka Trump's note that they are not a family of politicians. He's new to this, to the process of figuring out how to cobble together a delegate total and how to organize a campaign in a number of states at once. The process is clunky and complex, which is not entirely unintentional. It's a series of different events testing a different range of skills.
Trump's a good sprinter. That may not be enough to win the gold at the decathlon.