The first part of that headline is probably coming next week, if Rubio doesn't back off and aim every bit of his remaining ammunition at Trump, like every actual Republican should have been doing for the past eight months (Cruz included). Just as with Ben Carson, his campaign is effectively done and he needs to take one for the team and focus on the common task of preventing the de-conservativation of the Republican Party.
Trump? Heck, he'll try anything once:
Speaking at the Carolina Values Summit at Winthrop University, the Texas senator said that the “lawless” decision by the Supreme Court to [impose sodo]marriage nationwide was “judicial [extrem]ism.” And he indicated that Rubio and Trump, whom he did not identify by name but as his top two challengers, were flimsy in their opposition to [sodo]marriage.
Even though both oppose [sodo]marriage, each said they would abide by the “law of the land” last year.
“Those are the talking points of Barack Obama,” Cruz said.
The Supreme Court decision, he added, “will not stand.”
Trump does, indeed, support sodomarriage. As does Rubio, in the same mealy-mouthed fashion that many liberals claim to "personally oppose" abortion but defend it to the death in their public capacity. That judicial-review driven "law of the land is anything the Supreme Court says it is" mental illness is particularly aggravating for what a pure, white-flag-waving excuse it is. The law of the land is supposed to be the United States Constitution itself, which neither enumerates marriage governance as a federal power (leaving it, per the Tenth Amendment, to the States, or the people) nor grants the SCOTUS the power anywhere in Article III to impose its policy will on the country at large. Even Cruz isn't immune to it, but at least he's not bowing down to Obergfell and is proposing measures - calling for civil disobedience when government tries to silence pastors and forces them to perform homosexual "wedding" ceremonies (as is inevitable), various constitutional amendments to reiterate that marriage is a State matter, impose retention elections on the Supreme Court, and of course a federal marriage amendment (which Rubio avowedly opposes) to combat it.
It should be mentioned that under the Constitution, the POTUS has no authority to strike down a SCOTUS ruling; that power belongs to Congress, per Article III, Section 2 ("....the supreme Court shall have appellate Jurisdiction, both as to Law and Fact, with such Exceptions, and under such Regulations as the Congress shall make."), and Senator Cruz has yet to propose removing the Supremes' usurped marriage jurisdiction. Something that Rubio could use to great effect against his Texas rival if he hadn't already run up the rainbow flag and saluted it.
Regardless, Cruz would be trying to consolidate Palmetto State evangelical voters anyway, and this is another good way of framing Trump's pagan leftism; Rubio got included because, to quote the Knight Templar ...
For Trump's part, his thin-skinnedness at the well-targeted Cruz advertising offensive smacking him right in the mush is having its reflexive and amusing effect - of, in other words, he's back on the birtherism crap again:
It's an empty threat. Whether Trump would have standing to sue is conjectural, but no court at any level is going to throw Senator Cruz off of any ballot on those grounds; the Obama precedent speaks for itself. That that precedent is itself unconstitutional, and that Cruz is, in fact, not constitutionally eligible, would matter if the "American system" wasn't so hopelessly, parsecs-distant from constitutional boundaries already. Which makes it one of the strangest and bitterest ironies that there are Tea Party constitutionalists who are urging conservatives not to vote for the closest thing to a constitutionalist in the GOP field on that basis. It's like saying, "the friend of my friend is my enemy". And it illustrates the axiom that there's an exception to every rule - and the Constitution should not be a suicide pact.
The purpose of Trump's threat to Cruz now is the same as it was two weeks ago in Iowa, another evangelical-heavy State. He knows, whatever the polls might say, that Cruz can beat him in South Carolina (because he did so in Iowa), and that would be a springboard into Dixie-heavy Super Tuesday, where Cruz could run the table on him there and, at best, make it a long, uphill battle all the way to Cleveland, and at worst, put him away. So Trump is playing defense, and since he can't substantively out-debate Cruz nor help himself by attacking him from the Left, he's going to straight to the same ball shots that didn't work for him a week and a half ago. Is there any reason to believe they will be any more successful in a week from tomorrow?