Trump on Saturday retweeted a follower who said the Florida senator, who was born in Florida to Cuban parents, is not eligible to run for higher office. “I think the lawyers have to determine it,” Trump said on ABC’s “This Week,” when asked if he believed the tweet. “It was a retweet. Not so much with Marco, I’m not really that familiar with Marco’s circumstance.” When pressed on why he retweeted the claim if he wasn’t sure about it, Trump said he was trying to “start dialogue” about the issue.

Trump's mother, it should be noted, was born in Scotland, which is not part of the United States. His plane is registered in the Bahamas, also a foreign country. This fact pattern -- along with the wave of new questions surrounding what he claims is a birth certificate -- raises serious doubts about his eligibility to serve as President of the United States.

With Jeb Bush’s exit, the GOP establishment confronts an urgent decision: Either destroy Donald Trump or embrace him https://t.co/ezHDWFh9UC — NYT Politics (@nytpolitics) February 21, 2016

Think of it this way: WhyTrump entertain this nonsense again? His on-again, off-again (fake) obsession with Cruz's constitutional eligibility may not have worked in Iowa, but it has undoubtedly played a role in eating away at the Texan's favorability numbers among Republicans, which have taken a nosedive since Trump began targeting him with a withering barrage of attacks. Despite being born in Canada, Cruz is a natural born US citizen and fully meets the constitutional requirements for seeking the presidency. Rubio was born in Florida to Cuban parents. Like Cruz, he never went through the naturalization process because he was a citizen from birth, having been born on US soil. But here comes Trump -- perhaps sizing up the Florida Senator as his greatest threat at this stage of the race -- yet again returning to his fixation on eligibility conspiracies, which have now targeted three prominent political figures (Obama, Cruz and now Rubio). He's merely asking questions , you see:It's not "an issue" at all, even if a sizable number of Americans believe the current policy on birthright citizenship ought to be revisited. And is Trump really interested in "starting a dialogue" about whether or not children born to at least one foreigner on American soil are allowed to be president? As Cruz noted at the Fox Business debate in January, Trump may run into some complications himself under the theories he's been willing to indulge and amplify. Here's Ben Smith trolling back in 2011:This is all silliness, of course. Trump is just as eligible to be president as are Cruz, Obama, and Rubio -- the latter two of whom were born inside the United States. It's worth pointing out that Trump doesn't even believe his own storyline here; he's merely raising the "issue" as a means of bullying Cruz to bend to his will on unrelated issues, or risk a lawsuit. If the celebrity mogul genuinely thought that his GOP rival cannot be president under the constitution, he'd have no reason whatsoever to make his decision about mounting a legal challenge contingent upon the resolution of ancillary campaign squabbles. Similarly, he's only starting to hit Rubio on this because he may represent the clearest emerging obstacle to Trump securing the Republican nomination. When Trump feels threatened, he unleashes a wild flurry of attacks on his subject -- and no insult or accusation is beyond the pale. If it's Rubio's turn to face the deranged kitchen sink, we'll see if his plan to fight back is any more effective than the others who've come and gone before him. I'll leave you, depressingly, with this Significant elements of "the establishment" are reportedly moving rapidly towards a coalescence around Rubio, while others are seriously considering jumping on the Trump train.