This is not to suggest that Wehner—or anyone else for that matter—is remotely puzzled by Rubio’s behavior. As Wehner goes on to observe: “Senator Rubio strikes me as a person not only highly attuned to criticisms of him from the base, but overly reactive to them, adjusting and responding moment by moment. One senses that believing he badly hurt himself with the base because of his stand on immigration, he’s now scrambling to ingratiate himself with it. It isn’t a particularly impressive thing to watch.”

On this point, I have to disagree with Wehner. Even by the debased and debasing standards of modern politics, Rubio’s frenzied, shameless pandering to the GOP base is more than impressive; it’s genuinely breathtaking. Forget his current Cassandra act on the budget deal. Recall how brutally he threw his own immigration bill under the bus when it became clear that it was costing him support among conservatives. The Gang of 8 compromise passed the Senate in late June; by late October, Rubio was running around lecturing every reporter he saw about the need to ditch it in favor of the more “realistic” go-slow, piecemeal approach favored by House Republicans. As Rubio’s spokesman, Alex Conant, put it to TPM.com: “We should not allow an inability to do everything to keep us from doing something.” (The senator’s office declined to comment for this story.)

Ah, yes. Marco Rubio. Political pragmatist. Except when it comes to this week’s exceedingly modest budget compromise—then suddenly the man is as pure as the driven snow: a slash-spending, overhaul-government, brook-no-compromises, go-big-or-go-home guy.