Fair question from Amanda Carpenter:

Why would the establishment’s guy aim his fire at Mr. Populism now? He’s better off trying to elbow Walker, Rubio, and especially Kasich out of the race early, knowing that Republicans who hate Trump will eventually line up behind whoever’s still left in the center. Jeb thinks he can win a “Trump vs. Not Trump” race — and frankly, given the mood of voters, that may be the only race he can still win. Then again, if the candidates are supposed to be focused on winning their own “bracket” of the primaries right now, Ted Cruz should be running attack ads on Trump, right? And yet he isn’t. He’s his best friend in the race. So what’s going on here?

Two things, I think. One: The perception that Trump has “emasculated” Bush by jabbing at him with no penalty is hurting Jeb. No one likes a wimp, especially as a prospective C-in-C. As a matter of pure ape-like male dominance, he needs to hit back. And while it seems absurd for Bush, with his immigration record and donor-class backing, to attack anyone else in the race for being too squishy, it’s such an obvious point of attack on Trump that Jeb couldn’t resist. Trump is a fake conservative and Jeb’s not the only candidate who’ll end up making sure that voters know it.

The other reason to attack Trump is because, I think, Team Jeb still imagines themselves less as a member of the “establishment bracket” in the race than as the rightful frontrunner who’s destined to battle some yet-to-emerge more conservative candidate for the nomination. They’re attacking Trump simply because he’s the guy who’s momentarily blocking Jeb’s, er, right to rise in the polls; their assumption, I’d bet, is that once Trump has been neutralized and voters start looking seriously at the race, Bush will begin to float upward as the obvious centrist “adult in the room.” It’s not a matter of picking off voters from Trump, as Carpenter imagines, but rather a matter of restoring the rules of normal political gravity to a race that’s suddenly been transported to an alternate dimension where Donald Trump is a political phenomenon. To return to an analogy I used last week for Trumpmania, Jeb’s trying to begin the process here of exorcising the poltergeist. Then peace can reign in the GOP’s house again and we can all embrace the donor-anointed RINO who’s been tasked with losing with dignity to the Democrat in this new cycle.

As for the ad itself, you’ll notice that immigration is nowhere mentioned. That makes sense given the theme — immigration is a rare point on which Trump is very conservative — but reminds me of what Peter Beinart wrote about Jeb being too wimpy to stand up for his pro-amnesty position in the primary. He promised voters he wouldn’t run to the right yet here he is, bypassing an attack on Trump for conflating all illegals with the most violent criminals in order to hit him for being a RINO instead. Interesting. Also interesting is that one of the heresies Jeb does call Trump out on is his support for higher taxes on the rich, which … I’m not sure is much of a heresy among Trump’s grassroots fans, to be honest. When you’ve got conservative talk-radio stars shrugging at Obama-esque rhetoric about making hedge-fund managers pay their fair share, you know that Conservatism As We Know It is in flux. (See Ross Douthat for more on Trump’s populist tax pitch to blue-collar righties.) The fact that Bush would hit Trump on taxes in order to prove Trump’s not conservative is ironic in that Jeb’s right on the merits but is inadvertently demonstrating (again) that he and his team aren’t in tune with the mood of his own party’s base. At this point, Trump’s tax heresy is more of a heresy to Bush’s friends in the Republican business class specifically than to the Republican Party generally. Even when he’s on offense, Jeb’s making mistakes that will put him back on defense soon.