The geniuses in the Washington, D.C.- centered GOP establishment have a new plan to take down 2016 Republican frontrunner Donald Trump: Infiltrate his inner circle posing as an ally, then use their fabricated support of him to secretly plot to take him down.

But now they all admit: They were wrong, Trump is real, and he has a serious shot at winning this thing.

“Just like Humphrey Bogart said in Casablanca, I was misinformed,” Alex Castellanos, one such consultant, said of Trump in an interview with Bloomberg Politics on Friday. “He’s grown. He started off as the anti-Washington candidate, the angry man’s candidate, now he’s becoming not just an anti-them vote but a pro-him. He’s becoming the Make America Great Again candidate and that gives him room for growth.”

“Anybody who discounts Donald Trump—he’s going to be around through the convention now—I think is making a mistake,” Castellanos added.

From there, the conversation turned to how Castellanos thinks Trump might be taken down—and who might do it. He said:

Well you have two angles to look at that—he’s sitting on a bunch of people down there on the conservative side. He’s sitting on Ted Cruz. I doubt Ben Carson is going to do anything about that, but at some point Ted Cruz is going to wake and figure ‘this race is going to end and I’m never going to catch up.’ Then on the other side, the establishment side, you can wait a little longer. Whether it’s a Carly Fiorina or a Jeb Bush or a Marco Rubio, don’t stand in front of the tsunami right now and just coalesce—become a better, stronger candidate so you can be in the lead when everyone turns not to Trump but to the anti-Trump.

WATCH: CASTELLANOS DETAILS NEW PLAN TO TAKE OUT DONALD TRUMP

When asked, if he were running strategy for those wanting to take Trump down, how he would do it, he compared the effort to how Brutus murdered Caesar. ” Castellanos said:

The best way to do it is how Brutus killed Caesar. Get real close, snuggle up, and shiv him in the ribs. In other words, hug the message but not the messenger. ‘We understand the frustration in America, we know why you hate Washington. Your country is on the verge of decline, it’s going over a cliff, and nobody’s doing anything about it. We get it. Donald Trump and I agree on that, but let me tell you now what we’re going to do.’ Take his energy, take his heat, and use it to fuel your engine. Turn his heat into your action and be there, you hope, when voters actually get serious about this and say ‘you know what, I agree with him but he’s not a president.’

This is the same Castellanos who just a few days earlier called for a “cleansing” of the Republican Party after what he then expected would be an inevitable collapse of Trump’s campaign. Just a few days later, Castellanos has clearly changed his tune.