He was grumpy last night.

What set him off? Mostly it was NRO editor Rich Lowry ripping on him on Kelly’s show for matters various and sundry, but in particular for running a substance-less campaign on everything except immigration and, more recently, gun rights. “@RichLowry is truly one of the dumbest of the talking heads – he doesn’t have a clue!” tweeted Trump during the segment. To which Lowry replied:

Watch the clip below from the, er, Birther Report to see which line he means. The eternal question with Trump recurs here: Is he calling Fox out as part of a deliberate strategy or is he calling them out because brawling with people is just sort of what he does? Gabe Malor thinks it’s the former. Trump lost the debate to Fiorina, then he bailed on the Heritage Forum, and he’s been stuck talking about Muslims in his interviews ever since. The past week is the first time he’s showed any vulnerability in the race. So he’s reverting to what worked for him last month, attacking Fox as a mouthpiece for the RINO powers-that-be to goose Trump fans a bit. The conventional wisdom among Trump critics is that his shtick will wear thin as Republican voters digest more of it, week after relentless week. Here’s a fine test of that theory. Nominate Trump and this sort of thing is what you’re signing up for, over and over, potentially until 2020. My own theory is that he’s not doing this as a matter of strategy, to re-create his August heyday, but out of sheer instinct to hit back whenever you’re hit and trust that doing so will always redound to your benefit. It’s worked out pretty well for him so far, no? America hasn’t gotten tired of Trump’s shtick after 35 years in the public limelight. Why would Republican voters get tired of him now?

Two other points worth noting. One: Despite Jindal taking hard shots at him repeatedly for the past 10 days or so, Trump hasn’t hit back hard at him once as far as I know. That suggests Gabe is right and I’m wrong about whether Trump is attacking strategically or instinctively. He knows that squabbling with Jindal will only raise Jindal’s profile; as much as he may want to hit back, he has enough self-discipline to refrain when doing so would actually empower his enemy. Two: The retweeted shot at “Marco Amnesty” from one of his fans maybe presages the next stage in the campaign now that Walker’s gone, namely, the emergence of Rubio as the great establishment hope. If Rubio passes Jeb, Trump will probably turn the rhetorical guns on him full force as the GOP’s ultimate sellout on amnesty. Which might not be so bad for Rubio, actually: The contrast between the young, sunny, pro-immigration Latino and the older, angry, anti-immigration white populist is exactly the sort of dynamic Rubio needs to elbow aside Jeb and frame the primaries for the donor class and the wider GOP electorate as a choice between “the party’s future and the party’s past” or whatever. I’m not the candidate of amnesty, Rubio will say, I’m the candidate of inclusiveness, and he embodies it in a way that Jeb simply doesn’t. Trump’s better off ignoring Rubio for as long as he can and staying focused on Bush, the charmisa-less dynast, as the true face of the establishment.