Rubio’s right that this is a hypothetical and that nothing like the Gang of Eight bill could pass the House right now. But Mickey Kaus is right that it’s a darned fine gotcha, a way to gauge how far Rubio’s willing to go in renouncing his signature “achievement” as a senator. What if Rubio defeated Hillary next year and the party’s leadership decided to capitalize by doing something splashy to show Latino voters that the new, Rubio-led GOP was ready to engage them like never before? A bill like the Gang of Eight bill getting past the House isn’t inconceivable under those circumstances; if the new president wanted to give political cover to fencesitters in the House by backing the bill publicly himself, it might shake loose enough Republicans to get to 218 with Democratic help. Remember, Rubio’s main argument against comprehensive reform at the moment is that it’s politically impossible, and therefore pointless to waste more time on it since Congress will never have the votes to do it. A trailblazing new president might change that equation. So, again: Would he sign the bill? The fact that he won’t answer illustrates the primary/general straddle he’s trying to pull off. He won’t say yes because he knows that re-embracing the Gang of Eight at this point would horrify wary border hawks who are wondering whether to give him a second chance. But he won’t say no because, if he becomes nominee, he wants Latino voters and other pro-amnesty swing-staters to hold out hope that he might deliver on comprehensive reform as nominee. I wonder if some crafty moderator like Hugh Hewitt will pose this question to the field at one of the debates, receiving a drumbeat of no’s onstage until Rubio meekly pipes up, “That’s a hypothetical.” (Actually, Jeb would sign the Gang of Eight bill, right?)

The plan he offers Schieffer here in lieu of a straight answer sounds better than the Senate bill. Security must be “achieved” first (does that mean merely passing a security bill first or actually implementing the provisions?), then comes a reform bill to make immigration law more merit-based, and finally illegals get legalized — with citizenship a possibility years down the line. I wonder how many righties, having heard about Rubio’s about-face on the Gang of Eight bill, took that to mean he no longer supported legalization at all. Surprise! Schieffer misses an obvious follow-up, though: What happens if, as is certain, Democrats retain more than 41 seats in the Senate in 2017 and filibuster a security-first bill on grounds that they’ll accept nothing less than comprehensive reform? Is the first Latino president prepared to be demagogued from here to eternity for making his first immigration move as president a move to strengthen internal enforcement against illegals? What happens if, as is quite possible, Democrats do well enough next year to actually win back a majority of the Senate? Chuck Schumer isn’t going to start his tenure as majority leader by selling out the left’s pro-amnesty base in a deal with Rubio on border security, especially given the panic Democrats will feel from having lost the presidency to a Republican Latino candidate. They’ll be more eager than ever to re-ingratiate themselves with Latino voters. And, Schumer being Schumer, I’m sure he’d love to stick it to Rubio after Rubio abandoned the Gang of Eight by offering him a simple deal — namely, Senate Democrats will agree to the very same immigration bill that Senator Marco Rubio voted for, nothing more or less. If the House won’t agree to that, that’s fine; Schumer will be happy to watch President Rubio squirm as he’s forced to take sides with House Republicans against a bill that, uh, he himself helped write and championed for months.

Exit question: Did Rubio actually support … Mike Huckabee for president in 2008?