Once upon a time I would have cared. As it is, if you’re an anti-Trumper, what does it matter whether we end up in the Senate with a reluctant Trump backer like Cruz who’ll bend once his donors get grumpy enough or some establishmentarian backed by an enthusiastic Trumpist convert like Perry?

Frankly, if Perry thinks this is a hot idea, he should challenge Cruz himself. Which, if you believe this report, is a possibility.

Late this summer, former Texas Gov. Rick Perry strongly encouraged U.S. Rep. Michael McCaul to challenge U.S. Sen. Ted Cruz’s re-election bid in 2018, according to GOP sources…

“I think he’s spent a lot of time since Day One running for president,” McCaul said [of Cruz] in an interview with The Texas Tribune in Austin on Tuesday. “I think we deserve somebody in the Senate who is going to be representing the interests of the state of Texas.”…

Even amid Perry’s encouragement, it remains unclear if McCaul will follow through on a run. If he bows out, attention on a potential Cruz challenger could shift to Perry.

While the former governor was a loyal surrogate for Cruz during this year’s primaries — at least, once Perry was out of the presidential race — he was not always a fan. Perry was an ardent backer of Lt. Gov. David Dewhurst’s failed bid to win the open U.S. Senate seat that Cruz won. In his own 2016 campaign for president, Perry frequently alluded to Cruz as unready for the White House. Ultimately, Perry endorsed Cruz’s presidential run.

As of mid-August Perry was more popular in Texas than Cruz was, but that was back when Cruz was still pretending to stand on “conscience,” before the Mercers told him to cut it out. What I don’t understand, and what I haven’t understood since the months-long rumors about McCaul challenging Cruz first began swirling, is what the chief line of attack on Cruz in the primary would be. You’re not going to get to his right on policy. The only way to knock him off, I imagine, is to consolidate all of the Dewhurst/establishment votes — that was 43 percent of the primary vote in 2012 — and then find another eight points among pro-Trump Republican populists who hate Cruz for having made a show at the convention of not supporting Trump. In other words, for McCaul (or Perry) to win, the 2018 primary would to some extent need to be a referendum on supporting Trump this year even though Cruz has, belatedly, come around and done that. That would be a surreal strategy for Perry in particular given his own withering criticism of Trump when he was a presidential candidate for five minutes in 2015. What would his knock on Cruz be? “I came around on Trump very, very late but still slightly earlier than you”?

I assume Perry, if he ran, would run on pure name recognition/personal popularity plus the idea that things in Washington need to “get done,” with Cruz attacked for being less interested in passing conservative legislation than with grandstanding and filibustering. Running against a likable politician like Perry who can match him jot for jot in terms of conservative purity would be perilous. But that points to the likely political reality in 2018: If Clinton wins, conservative populists in Texas and beyond will really enjoy watching Cruz grandstand and filibuster for two years. A government shutdown or two to stop some Clinton initiative will make for excellent PR for him in 2018. Cruz will move quickly to position himself as one of Hillary’s most dogged antagonists in the Senate, and that’ll work well enough, I’d guess, to make McCaul or Perry forget about primarying him after all.

For a primary to have a chance of succeeding, I think, Trump would have to win next week, making Cruz’s loyalty this year a more germane issue in 2018. But even if Trump did win, there’s every reason to think Cruz would be brought to heel in the Senate and would spend most of the next two years working with the Trump White House in order to win back the pro-Trump populists in Texas who disdain him now. Trump might even end up endorsing him in 2018. Cruz wouldn’t be vulnerable unless he stood on principle against Trump for the next two years, trusting that there are more true-believing conservatives in a primary in Texas who’d respect him for that than there are moderates and Trumpers who hate his guts and would be eager to toss him out. I think he’s learned his lesson the hard way about just how “conservative” the conservative base, though. He’ll stay on whichever voters’ good side that he needs to in order to make a primary seem futile. We won’t just find out who the next president is next week. We’ll find out whether Ted Cruz is going to be more or less nationalist in his orientation in the Senate in Congress’s next term.