Fox News host Tucker Carlson has done a whole lot of devilish work to defend President Trump. As this blog has noticed, the nimble TV debater has used his highly watched program to belittle a whole range of Trump critics, all the while protesting that he was not defending Trump and his minions. Even though he was.

Not on Tuesday night, however. “President Trump, you’ll remember, ran for office promising to fix immigration, make good deals and, in general, do a better job than the corrupt, incompetent lawmakers, he said, were wrecking the country. And he was right, they were wrecking the country,” said Carlson. “And yet, today, in a remarkable twist, the president held a televised meeting with the very swamp creatures he once denounced. He told them he trusted them to craft immigration policy without his input.”

Correct: Trump on Tuesday allowed White House reporters to hang out at a bipartisan immigration discussion with Capitol Hill lawmakers. The session impressed the living hyperbolights out of daytime cable television. “I’m sure I will get hit for this and I don’t really care,” said CNN chief political correspondent Dana Bash on the cable network. “The bottom line is that this is, a year ago, this is the presidency that many people thought Donald Trump was capable of.”

That group of people doesn’t include Carlson, who saw a belly flop unfold on the White House table. The host highlighted how Trump told the lawmakers, “When this group comes back, hopefully, with an agreement, this group and others from the Senate, from the House, comes back with an agreement, I’m signing it. I mean, I will be signing it.” Huh?

Also troubling Carlson was the president’s apparent position, at the meeting, that he’d sign on to a resolution of the predicament of the “dreamers” — about 700,000 people who came to the country illegally as children, and who were protected under President Barack Obama’s Deferred Action for Childhood Arrivals (DACA) program — without tethering the matter to broader immigration-reform measures. “Amnesty for DACA recipients is the only leverage the White House has,” ripped Carlson. “Once the president agrees to let them jump to the head of the line, ahead of millions of other people hoping to come here legally, the negotiation is over. At that point, why would Democrats agree to anything? Ending chain migration, the diversity lottery, supporting a merit-based system that might actually help America? No chance.” (On Twitter, the president issued this walk-back).

The notion that Trump was highlighting his deference to Congress riled Carlson: “If these are the same people the president now says he trusts to write the immigration bills, the one he will sign no matter what it says, so what was the point of running for president?”

Good question, Tucker Carlson!

With that, Carlson tossed out a year-old MO — playing the anti-anti-Trump card, that is — and went straight after the president. The reason is that Trump’s remarkable flexibility bumped up against the closest thing that Carlson has to a substantive core: a hard-line posture on all immigration issues. Time and again, Carlson has demagogued on such issues for his audience, whether the topic at hand is general immigrant crime, an alleged rape at a Rockville, Md., high school or the difficulties experienced by a Pennsylvania community in living alongside a group of Roma immigrants.

Which is to say: Carlson can look the other way when Trump shows his childishness on Twitter; he can look the other way when a Trump appointee pleads guilty to some federal crime; he can look the other way (quite easily) when Trump expresses contempt for a free press. Any weakness on immigration, however, shall not be tolerated. The Tucker Carlson base will not have it.