Apart from one stray Rasmussen poll in early August that had Rubio tied with Jeb Bush at 10 percent, this is the first poll since the start of Trumpmania in June that’s placed him as high as second. And that Rasmussen one seems to have been an outlier in hindsight: It also had Trump at 17 percent, the only poll taken in the last two months in which he hasn’t cracked 20 percent.

Shake up:

Rubio’s the only candidate among the top six to have gained more than two points since the debate on September 16th. (Surprisingly, Carly Fiorina’s only improved modestly despite her own universally praised debate performance.) How’s he doing it? Probably through inheriting Scott Walker’s voters, by and large, and possibly picking up some of Trump’s lost support. That’s the only way I can explain how Rubio would be the sole major gainer while Trump is the sole major loser, even though it’s not at all intuitive that people who like the plain-spoken hardline border hawk would migrate over to the polished pro-amnesty candidate. Maybe some of Trump’s early support was soft, consisting mainly of people who preferred him due to simple name recognition and have come to like Rubio after watching him at the debates.

More important to Rubio than being in second here, arguably, is that he’s more than doubled Jeb Bush’s support. Bush’s numbers are almost perfectly static since the last poll taken two weeks ago, and this marks the fourth major poll in a row in which he’s trailed Rubio — although never by this much until now. That’s why Jeb feels he can’t wait any longer to start hitting him. Well, that and the fact that Rubio, almost alone among Republican candidates so far, hasn’t suffered much from Trump attacking him. As Trump likes to say, Bush, Rick Perry, and Rand Paul all seemed to dim in the polls after they started swinging at Trump (or rather, after Trump started swinging at them). Trump’s been calling Rubio a “clown” for two weeks now. How’s that working out?

As for Trump’s own polling, in the last seven major national polls taken, he’s reached 26 percent just once. Here’s what his poll average looks like in September. Remember, the debate happened on the 16th.

If you’re wondering why RINOs like me have been wondering lately whether he’s hit his ceiling, that’s why. Because … he really might have hit his ceiling, despite the fact that he still leads. If the RCP numbers don’t convince you, have a look at the trend in his favorable rating that YouGov found today. The blue line is “favorable,” the green “unfavorable”:

That’s a 12-point drop in his favorables among Republicans and a 13-point rise in his unfavorables. Who’s driving that? My initial guess was that it was women who were annoyed by his wisecrack about Carly Fiorina’s, and it’s true — if you compare his favorable rating in mid-September with his rating now, you’ll find it’s declined among women. Previously it was 38/55; now it’s 33/62. That’s women generally, though, not Republican women specifically, so there’s no easy conclusion to draw about the drop in his favorables among Republican voters. There is, however, another group more closely associated with the GOP within which Trump has suffered even sharper losses. Ta da — it’s conservatives, who split 57/35 in Trump’s favor before the debate and now split 50/46, a perilously narrow margin for a guy selling himself as the great hope of conservative populists. Maybe those Club for Growth ads attacking him on his fiscal priorities are starting to bite. That would also explain why Trump seems to have hit a ceiling overall: If he’s begun to lose conservatives because of his record as a liberal, realistically there’s no way he’s getting them back. He told CNN last night that if he fell badly behind, i.e. to one or two percent, he’d get out of the race. That’s unlikely to happen, but what if he fell to, say, 15 percent while Rubio and Carson both bounced out to a steady 25-30 percent? Would that be enough of a margin for him to quit?

Lots of good news in this poll for Carson too, needless to say, as he’s still a strong third (with more second-choice voters than Rubio). He just banked an amazing $20 million in his third-quarter fundraising, an astounding haul for a guy who’s relying mainly on small contributions, not truckloads of dough from the wealthy a la Jeb Bush. By comparison, Rand Paul — the one-time great hope of the Ron Paul revolution — pulled in just $2.5 million last quarter. Yeesh. In lieu of an exit question, here’s Trump taking the “Green Lantern theory” of the presidency to its logical conclusion.