To some lefties, Trumpmania is a form of karmic payback for the GOP establishment having spent the past seven years pandering to conservative populists in their hatred of Barack Obama. They nurtured the tea-party monster for their own ends, the theory goes, but now it’s broken out of the lab and transformed into Trumpism, which they can’t control and which might very well end up killing them. If you like that theory, you’ll love the idea of Trump recycling a famously fringy attack on Obama to try to take down Mr. Tea Party himself, Ted Cruz. That could actually work out pretty sweetly for the establishment if Trump uses this to sink the formidable Cruz and then gets steamrolled by Rubio in a one-on-one battle for the nomination, but let’s not sweat the details. If you’re a liberal, you must be enjoying this immensely.

Back on December 7, when a poll dropped showing Trump suddenly trailing Cruz in Iowa, I wondered how long it would be before Trump started idly wondering aloud whether Cruz is eligible to be president. We have our answer — although I assume Trump would say that he’s not questioning Cruz’s qualifications here, he’s merely repeating what others have said to him. It’s their attack, not his. Heaven forbid.

“Republicans are going to have to ask themselves the question: ‘Do we want a candidate who could be tied up in court for two years?’ That’d be a big problem,” Trump said when asked about the topic. “It’d be a very precarious one for Republicans because he’d be running and the courts may take a long time to make a decision. You don’t want to be running and have that kind of thing over your head.”

Trump added: “I’d hate to see something like that get in his way. But a lot of people are talking about it and I know that even some states are looking at it very strongly, the fact that he was born in Canada and he has had a double passport.”…

In the interview with The Washington Post, Trump said he was providing a candid assessment of his leading opponent rather than initiating a personal attack and reviving the “birther” debate that he once led against President Obama. He repeatedly said he is hearing chatter on the topic among voices on the right. “People are bringing it up,” he said.

You believe him when he says he’d hate to see this get in Cruz’s way, don’t you?

Follow the bouncing ball here. Trump was first asked about Cruz’s eligibility in August 2013, just seven months after Cruz joined the Senate. ABC wanted to know whether Trump, who’d spent so much time demanding Obama’s birth certificate in interviews, thought Cruz was eligible for the presidency after being born in Canada to an American-citizen mother. Trump’s reply: “If he was born in Canada, perhaps not.” Fast-forward to March 2015, with Cruz already in the race and Trump preparing his own candidacy. Trump said this of Cruz’s eligibility:

“Well he’s got, you know, a hurdle that nobody else seems to have at this moment,” said Trump, who was born in Queens. “It’s a hurdle and somebody could certainly look at it very seriously. He was born in Canada … if you know … and when we all studied our history lessons … you’re supposed to be born in this country, so I just don’t know how the courts would rule on it. But it’s an additional hurdle that he has that no one else seems to have.”

Similar to today! But a few days later, he assured NRO that Cruz’s situation was “very different” from Obama’s because Cruz “has been very candid and open about his place of birth and his background.” Fast-forward another six months, to September 2015, and Trump was even more confident that Cruz was in the clear:

“I hear it was checked out by every attorney and every which way and I understand Ted is in fine shape,” Trump told ABC News just before speaking at a Capitol Hill rally blasting the Iran nuclear deal…

“I think he’s a really nice guy, I’ve gotten to know him a little bit, but I think if he’s born in Canada it’s a problem no question about it,” he said during an interview at Washington’s iconic Old Post Office, which Trump recently acquired and is transforming into a luxury hotel.

It’s still a “problem” at that point — but not much of one given that the lawyers have checked it out and everything seems shipshape. How do you get from that to wondering whether Cruz might end up snared in years of litigation over his eligibility? The answer, of course, is that the Trump/Cruz bromance was still going strong in September, with Trump leading Cruz handily in every poll. Four months later, Cruz is ahead in Iowa and leads Trump narrowly in a new poll today out of delegate-rich California. As Trump feels increasingly desperate, it may be that he’s going to go increasingly Birther on Cruz. Which is a mixed bag for Cruz, I think. On the one hand, if Trump convinces his fans that Cruz isn’t constitutionally eligible to be president, that’s a major problem for Cruz’s strategy of winning over Trump’s populist base. On the other hand, my hunch is that conservative talk radio will be merciless with Trump if he presses this line of attack. And Cruz will get some sympathy even from righties who might not otherwise look warmly upon him if Trump insists on painting him as some sort of foreigner who should have his presidential hopes cashiered by a judge at a moment when he’s winning. How does that shake out? Does Cruz gain or lose votes on balance? And if Trump goes all-in on Birtherism, how does he endorse Cruz later if/when he drops out, as Cruz is surely hoping he’ll do? You can’t support a candidate whom you believe isn’t eligible to run.

Cruz has responded, incidentally. This is as close as we’re going to get to him throwing a straight punch at Trump, I think:

My response to @realDonaldTrump calling into question my natural-born citizenship? https://t.co/gWfAHznlCY

— Ted Cruz (@tedcruz) January 5, 2016

Meh. That’s actually pretty dismissive of Trump to anyone who gets the reference (which most everyone does, I hope?), but it’s cheeky enough that Cruz can probably play it off as a joke if Trump gets cranky and wants to fight. Michelle Fields is reporting on Cruz in Iowa for Breitbart and says that he scrupulously avoided hitting Trump harder tonight when reporters cornered him after an event, so … yeah. Cruz is probably done with this to the extent he can be. Your move, Trump. Escalate or not?