It looks like Marco Rubio's plan to defeat Donald Trump is the same plan that everyone else has used: Ignore him and hope he goes away.
"[...] I don’t have any voters begging me to attack anyone," he said. "Second, I think that’s a media narrative that a lot of people in the media want to see Republicans attacking each other because it makes for good television. I’m not in this race to attack any Republican. I’m more than happy to show differences … and we’ve been able to do it."
Nobody wants to be the person who attacks Donald Trump. Nobody wants to be that person because Donald Trump, for all his hundreds of faults, is very, very good at the sort of insult comedy that quickly cuts serious politicians down to size. Jeb Bush was, after all, low-energy. Ted Cruz is, indeed, the candidate running the lying-est campaign. And Donald Trump has been very, very good at making those attacks stick.
So no, Marco Rubio doesn't want to attack Trump if that means becoming Trump's next target. His strategy—again, the strategy of the entire Republican establishment, and you can see how well that has been working out for them—is to be the last non-Trump candidate standing. Then, the theory goes, a miracle happens.
Trump, on the other hand, knows this. And he's perfectly happy to remind Marco Rubio of the wrath that would await him if Marco Rubio piped up against Donald Trump. He uses his own vitriol as a weapon to be unleashed or held back, according to who is or isn't being nice to him.
"[...] I wouldn't want to go that far. But so far, he's been very nice and I think I've been very nice to him," Trump said. "We haven't been in that mode yet, but probably it will happen, and if it doesn't happen, that would be a wonderful thing. I mean, it would be very nice. But that's a possibility that it will happen."
Again, though, each of these Republican candidates is campaigning on the notion that they are tough would-be leaders who will handle our international adversaries with far greater "strength" than the hapless Obama could muster. And not a one of them, so far, has even been able to win an insult war against Donald Trump.
