Carson assumed the lead because he's seen a huge rise in support over the past few months. Support for Trump, as we noted on Tuesday, has stayed pretty consistent; Carson simply rose up to meet him.
You can see that clearly in the Quinnipiac trend since August. (All the Quinnipiac poll data is here.)
Carson keeps heading upward. Sen. Marco Rubio (Fla.) is heading upward, too. (This is the first poll completed entirely after the third Republican debate.) But his rise doesn't yet match Carson's. Jeb Bush, meanwhile, hits a new low. The man from whom Trump snatched the lead is now in fifth place, in that bottom tier of support, with four percent of Republicans deigning to give him a thumbs up.
But let's not talk about any of that. Let's talk about Ted Cruz.
The senator from Texas is there alongside Rubio in the big-picture polling. But when we break out demographic groups — noting, of course, that the margins of error here are higher — something interesting happens.
Here they are; analysis below.
So Carson's surge is clearly bolstered by his support from evangelicals. (And he's helped by Trump's weakness with women.)
But notice the tea party and conservative buckets: There, Cruz is at or near the lead. And that's a big group that comes out to vote. Rubio's support is pretty much the same in each category. Cruz has clear areas of strength. That's the value proposition of each: Rubio does better with moderates, now passing Bush, and does okay with everyone else. Cruz is the right's candidate. (Rubio clearly suffers from the amount of moderate support for Trump and Carson. We'll see what happens there over time.)
Carson's surge moved him past Trump and into the lead. In 2012, other new faces did the same thing, only to quickly fall back away. We'll see what happens with Carson. The story today, though, is that we've seen our first shake-up in the Republican polling in a long time — and we can now clearly see Cruz, lurking in the far-right wings.