Skip to 4:55 of the clip below for the key bit from yesterday’s “Face the Nation” interview. Pop quiz: Who said the following, and when did he say it — and to whom?

We have a crisis on illegal immigration. Neither party is serious about stopping it. I strongly oppose illegal immigration. I categorically oppose amnesty. I support legal immigrants who come here supporting the American Dream.

I come from the perspective of someone who spent much of my adult life in law enforcement. In a post-9/11 world, it is absolutely unacceptable that we don’t know who comes over our borders. We need to do everything humanly possible to secure the borders. Electronic surveillance, a wall, helicopters and, most importantly, boots on the ground. If elected, the first thing I will do is triple the U.S. Border Patrol.

That’s Senate candidate Ted Cruz, speaking to Dustin Siggins in May 2012 in an interview for … HotAir.com. Three years before the GOP presidential primary got going, he was calling for a border wall in the border state of Texas. And not just parts of Texas, either. As Cruz made clear in a Senate primary debate that year, he wanted the entire Texas border walled off — even if it meant invoking one of Trump’s favorite federal powers, eminent domain, to do it.

Cruz also distinguished himself from Dewhurst with his full-throated support for a border wall estimated by the Department of Homeland Security to cost $7.3 billion, or $6.5 million per mile.

Cruz defended the border wall proposal even if it meant expropriating private property—a position that the debate’s moderators, WFAA reporter Brad Watson and Gromer Jeffers of the Dallas Morning News, said contrasted with Cruz’s message of fiscal conservatism.

“One of the specific powers and responsibilities of the federal government is to secure the borders,” Cruz said. “Property can be taken with due process of law and just compensation.”

That was July 2012. One of the evergreen questions with Trump is whether he’s merely misinformed or whether he knows the truth and is twisting it to suit his own ends. Which do you suppose it is for the “Cruz wouldn’t have supported a border wall without me going first” claim? How about the additional claim he makes that immigration wouldn’t have come up in the primaries if not for Trump forcing the issue? You think Ted Cruz, running to Marco Rubio’s and Jeb Bush’s right, would have given them a pass on their past support for amnesty, do you?

As always with Trump, there’s a kernel of truth beneath the lies and blather. There’s no denying, I think, that Cruz has been pushed further right than he would have gone if Trump had passed on the race. The most glaring example is his position on legal immigration. Until recently, Cruz always hedged his condemnations of amnesty with professions that there was no greater champion of legal immigration than him. In the immigration plan he released in November, though, he reserved the right as president to limit legal immigration depending upon the state of unemployment in the United States. That was his counter, I think, to Trump’s mass deportation plan: If Cruz couldn’t go along with “deport ’em all” sentiment for fear of how it might hurt him in the general election, he’d at least throw border hawks a bone by sounding a bit more like Jeff Sessions. His recent categorical refusal to legalize illegals as president was also driven mainly by fear of Trump, I suspect. Granted, it was Rubio who drew that out of him by publicizing his 2013 amendment to the Gang of Eight bill that proposed more work permits for illegals, but Cruz probably could have stood firm on that position if Trump wasn’t in the race. He wouldn’t have needed to move further right in a one-on-one battle with Rubio; even if you take a dim view of Cruz’s amendment, his immigration credentials are still unquestionably better than Rubio’s. With Trump running to Cruz’s right, however, the calculus changes. If Cruz were to signal support for legalization in any way, Trump would destroy him over it and that would ruin Cruz’s long romance with Trump’s voters. Result: Cruz now vows he’ll oppose legalization “today, tomorrow, forever.” It’s not the border wall that left Cruz exposed on immigration, it was everything else.

That’s what Trump should have said here, but maybe he’s just warming up. Note what he says at 6:04 about how Rubio and Cruz were both weak on immigration in the past. That’s an early hint, I think, that he’s prepared to come after Cruz hard on amnesty if Iowa remains close over the last few weeks. If he does, the outcome on caucus night will give us a solid verdict on whether Trumpmania and the primaries writ large are really “about” immigration or whether there’s more to the vote this year than that. If Trump wins the state by taking Cruz down over his 2013 amendment, that’ll tell us a lot. If he fails, that’ll tell us a lot too.