After an early career as a conservative operative dedicated to bringing down Bill Clinton, David Brock has emerged as one of the top guys in the world of Democratic-aligned fundraising, messaging, and opposition research. He runs Media Matters, an all-purpose progressive operation, and Correct the Record, which is specifically dedicated to 2016 presidential campaign matters. And according to Politico's Annie Karni, he said something really weird on Friday about Marco Rubio.

The main point of Karni's article is that Brock is getting ready to unleash material on Ted Cruz, which makes a lot of sense, since Cruz is emerging as a very plausible GOP nominee. But Brock claims to be so confident that Cruz will win, he's not even going to bother doing oppo on Marco Rubio, which is bizarre (emphasis added):

Brock said he doesn't dismiss what he characterized as an outside chance that Donald Trump could win his party’s nomination — "You never discount a demagogue" — but said he is not prepared to pour resources into planning for the rise of Sen. Marco Rubio. "I just don’t see it," he said of the young Florida senator. "He has some critical weaknesses, his absenteeism, weird listlessness on the campaign trail, all the mess with his personal finances — there’s a lot. He hasn’t been vetted." "I think Cruz will end up as the nominee," Brock added, "and I think Trump will support him and have a big platform. We’ll be hearing from him at the convention and on the campaign trail."

What is going on here? I can think of five possibilities:

Brock actually believes that Rubio's odds of winning are so low that it's not worth bothering to research him. I never like to write off the possibility that people are saying what they mean, but this just seems too ridiculous to be true. I happen to think the current conventional wisdom is overrating Rubio's odds, but it's clearly a real possibility. Brock already has the goods on Rubio. Rubio's campaign has been dogged by unsubstantiated rumors that he has a secret second family. If Brock has persuasive evidence in his back pocket that this is actually true, then he could be simply keeping his powder dry hoping to destroy Rubio's reputation at some future time. Unlike No. 1, this is at least logical, though obviously the "whoa if true" factor is enormous. Brock thinks Rubio is a weaker general election candidate than Cruz. The GOP is currently undergoing a hotly contested primary campaign. Focusing on anti-Cruz oppo and ignoring anti-Rubio oppo could be seen as a way of helping Rubio win the nomination. Brock might want that outcome if he thinks Cruz is more electable than Rubio. I can't imagine why Brock would think that or how he would convince his staff and donors that it's true, but people develop weird ideas. Brock is using reverse psychology. Imagine scenario No. 3, but the opposite. Brock agrees with me that Cruz is the least electable candidate in the GOP field (yes, including Trump). Brock desperately wants to help Cruz win the nomination and worries that his unelectability will hurt him in GOP primaries. By pretending to be afraid of Cruz, Brock can help Cruz persuade Republicans that he — rather than Rubio — is the candidate Democrats fear. I don't normally like to posit elaborate conspiracy theories, but the first three theories are so weird I'm throwing this one out there. Brock's taken a deep dive on Rubio and can't find anything. The rumors referenced in No. 2 seem to be hurting Rubio in the invisible primary. But it's possible that one reason nobody has substantiated them — or related rumors of financial improprieties — is that they aren't true. If Correct the Record starts dumping on Rubio but doesn't have any juicy dirt, that might help convince Republicans that the dirt simply doesn't exist. That would help Rubio win the nomination, which Brock doesn't want because Rubio is the candidate Democrats fear. The problem here is that even if all the component elements are true, it still doesn't add up to a very persuasive reason not to release some anti-Rubio spin — scandals aside, the guy has a long, not-well-known record in Florida politics that surely includes some stuff worth criticizing.

None of these theories seem very compelling to me. I'll note that this all came up during a speech Brock gave in Cleveland, so it's at least conceivable he was just bored and screwing around for no real reason.