Noah already wrote a policy rebuttal to Paul’s position, which Paul elaborated on this afternoon in a new op-ed at Time. (The op-ed, unlike his tweets, doesn’t mention Rubio by name. Although it does approvingly cite … George W. Bush?) Anyone want to make the case that the politics of attacking Rubio on this issue were smart, at least? I can’t figure out why Rand would do it.

When I tweeted out my surprise a few hours ago, a dozen people tweeted back, “Maybe Paul’s just saying what he really believes.” No doubt. But the thing that distinguishes Rand from Ron and what makes him a legit contender for the nomination is that he’s willing to temper his foreign policy positions in order to make himself more appealing to mainstream conservatives. Remember when he complained earlier this year, as things got hairy in Ukraine, how certain Republicans (*cough*McCain*cough*) always seemed to want to “tweak” Russia? That was a fine libertarian/paleocon sentiment. A few weeks later, after Putin had gotten more aggressive and conservatives were demanding that Obama show some muscle, Paul took to Time magazine to demand “strong action” against Russia. Remember when he scoffed at the idea of intervening again in Iraq, with the U.S. effectively serving as “Iran’s air force” by bombing ISIS, only to decide a few months later as conservatives rallied for force that he would seek to destroy ISIS militarily as president? Last month he introduced a bill to formally declare war on the group that would even allow ground troops in certain limited circumstances. Remember when he seemingly endorsed containment of Iran on ABC’s Sunday news show, only to come back the next week after the predictable uproar on the right ensued with an op-ed insisting he was “unequivocally” not for containing Iran? It’s not just conservatives who’ve noticed these reversals. Members of Paul’s libertarian base like Jacob Sullum and others at Reason have noticed them too. And everyone understands what it’s about: Rand’s afraid that if he takes a traditional libertarian line on hot-button foreign policy matters, it’ll be too easy for 2016 rivals to convince tea partiers that he’s just like his old man after all and can’t be trusted to protect America. Watering down his libertarian impulses may be cynical, but it’s smart.

So … why pick a fight with Rubio, then? It would have been easy for him to oppose the embargo while hedging enough to make conservatives comfortable with his position. E.g., “I believe in the liberating power of trade and support lifting sanctions on Cuba, but I’m concerned that Senator Rubio is right that this will mainly be a windfall for the Castros, not the Cuban people. The president needs to do more to ensure that the benefits of trade flow to the public, not to the regime, starting with demanding democratic reforms.” At the very least, he should have emphasized the point made by Noah, Michael Brendan Dougherty, and many others that tossing a bunch of capital into a corrupt, cronyistic socialist swamp with no meaningful civic institutions is likely to produce a fascist oligarchy like modern Russia, not a truly free state. But Rand didn’t hedge; instead he went right at Rubio, mocking him with a too-cute-by-half crack that Rubio’s the real isolationist. Why? Why, with the primary campaign just weeks away from going full tilt, would he suddenly refuse to pander to a position that probably 85 percent of the right-wingers he’s trying to woo hold? And not only is his position one that’s disfavored by the right, however ambivalent the rest of America might be about the embargo these days, it’s one that righties will forever associate with Obama and his foreign policy “legacy.” Paul may think he’s waging war on Rubio on behalf of libertarianism but I bet most conservatives will see it as him waging war on behalf of Obama. It doesn’t even make sense at the micro level: As Harry Enten explains, while Cuban-Americans generally may be more conflicted about the embargo than they used to be, Cuban-American Republicans in Florida aren’t. And those aren’t the kind of voters you want to alienate if you’re eyeing the GOP nomination.

These Cuban-American Republicans could easily swing a relatively close Florida Republican primary. Cuban-Americans make up a sizable 8 percent of the primary vote in Florida, which is greater than the 6 percent Cuban-Americans make up in the general election. More importantly, though, Cuban-Americans have voted in a bloc in the past two presidential primaries.

In 2008, Cuban-American voters in Florida cast 54 percent of their ballots for John McCain compared to just 32 percent for Rudy Giuliani. McCain actually lost among white voters to his nearest rival, Mitt Romney, but was able to win the primary by 5 percentage points primarily because Romney won only 9 percent of the Cuban-American vote.

In 2012, Cuban-American voters switched their allegiance to Romney. He won 57 percent of the Cuban-American vote in the primary, while Newt Gingrich won only 31 percent.

As a swing state and an early state that follows Iowa, New Hampshire, and South Carolina, Florida’s arguably the single most important Republican primary in catapulting its winner to the national nomination. McCain won it in 2008, Romney won it in 2012. Whatever chance Rand Paul had to win it is smaller now, maybe considerably smaller, than it was yesterday.

So, again: Why? Why would Rand unload on Rubio knowing that he’ll be accused of carrying Barack Obama’s water on foreign policy? “He believes in his position” is no answer; as I’ve explained, that’s never stopped Rand from moderating before. One Twitter pal theorized that maybe Paul hit hard here because he wanted to stand out in the field. But … that’s my point. He already stands out! He stands out so much on foreign policy that he’s spent two years trying to stand out less, knowing that it’s a potential liability for him. Another friend speculates that Paul likes the “you’re the real isolationist!” line so much that he couldn’t resist throwing it in Rubio’s face, even if it means stridently opposing conservative orthodoxy in this case. When Rubio or Jeb Bush calls him an isolationist at the first presidential debate next year, Rand now has a ready comeback. The problem there, though, is that it won’t just be Rubio or Bush who’s calling him that; it’ll be the entire field, Christie, Walker, Huckabee, you name it. If mainstream conservatives watch 20 different big-name Republican pols assure them that Paul’s dangerously naive on Cuba, how much counterweight will Paul saying “no, you’re the naive one!” really have? Worst of all, perhaps, Paul’s devoted the past year to building the case that, as a “realist,” he’s actually the true heir to Ronald Reagan on foreign policy, not Rubio and the rest of the superhawks. What’s his counter now, though, when Rubio reminds him that the Reagan administration kept the embargo in place? It feels like he’s blowing himself up here on what would otherwise have been a boutique issue in the primaries, except for one key primary where it really matters and Paul’s bizarrely on the wrong side of it.

Anyway. Ed tells me that he put this question to Mitch McConnell in interviewing him for the Hugh Hewitt Show tonight, which should be airing within the hour after this post goes live. That’s quite a dilemma for McConnell — Paul is his close ally, a guy who helped him get reelected to the Senate and whom McConnell has already said he’ll support for president, but Rubio represents the balance of conservative opinion. Which man did McConnell side with? Listen and find out.

Update: Some commenters are arguing that most Republican primary voters won’t care much about Cuba so this doesn’t hurt Paul really. Maybe true — but not in Florida, which is a big problem for Rand as I explained above (and as Ian Tuttle explains here). It’s not even Cuba per se that’s risky for Paul; it’s the perception that he’s so much different from other Republican candidates on foreign policy that he’s more inclined to agree with — gasp — Barack Obama than he is with Marco Rubio and the rest of his own party’s candidates. Opposing the Cuba embargo might please libertarians but it probably won’t him many extra conservative votes, especially in the primaries. Being seen as simpatico with Obama’s approach to international relations could hurt him, though, with exactly the sort of righties he’s targeting for votes.