The Des Moines Register’s longtime pollster Ann Selzer identified the surge of first-time Democratic caucus-goers who would carry Barack Obama to victory in 2008. Her final poll before the 2012 Republican caucuses caught the strong upward momentum for Rick Santorum. Her last snapshot before this year’s caucuses for the Des Moines Register and Bloomberg Politics correctly saw a close race between Hillary Clinton and Bernie Sanders, with fewer first-time participants than eight years ago.

But Selzer’s view of the GOP campaign was unfortunately off the mark in several respects: putting Donald Trump ahead of Ted Cruz, underestimating turnout overall and particularly among evangelicals, and missing the late swing toward Marco Rubio that some political observers sensed by watching the campaign on the ground.

Yesterday Selzer commented to David Weigel of the Washington Post,

“In all the press I did in the last two days—and it was a LOT — I talked about the fluidity,” she wrote in an email. “Up to the last moment — including inside the caucus room — campaigns and supporters are working for change! Surprise! Big evangelical turnout — no doubt the biggest.” […]

“Trump was disliked by vast majority of caucus-goers who didn’t support him,” Selzer said. “Bernie’s extraordinary strength was with first-timers, who showed up in above-projected numbers. […]

“If I’m demoted to ‘silver standard,’ I’m fine with that,” she said. “I was never all that comfortable with the hype.”

Selzer can take some comfort in knowing that the last ten Iowa polls released before the caucuses all put Trump ahead of Cruz. The most recent poll to show Cruz leading was the Iowa State University/WHO-TV survey, which uses an unconventional screen for likely caucus-goers. But Iowa State/WHO understated support for Trump and Rubio. Given the tremendous difficulties involved in polling the Iowa caucuses, especially on the Democratic side, we should expect some misses, even from the top professionals in the field. As the presidential campaign progresses, here’s hoping political journalists will focus less on poll-driven horse race coverage.

UPDATE: Selzer did some “Tuesday morning quarterbacking” of her final poll in today’s Des Moines Register. I enclose excerpts below.

From a commentary by Ann Selzer for the February 3 Des Moines Register, “Tuesday morning quarterbacking the Iowa Poll.”

We knew Ted Cruz held a strong lead with evangelicals. And we knew evangelicals traditionally show up in above-average proportions. Our poll said they were a little less than half of likely caucusgoers. […] Historically, however, evangelicals have been closer to 60 percent of the Republican vote on caucus night — 57 percent in 2012 and 60 percent in 2008. So we tested a scenario using 60 percent. That closed the gap between Trump and Cruz to a one-point race, but Trump still led.

On caucus night, the unprecedented turnout (about half again as many as showed up in 2012) included 64 percent describing themselves as evangelical or born-again Christians, beyond anything in recent memory and what anyone might have speculated. Obviously, had we tested that scenario, we would have seen a Cruz victory. We knew Cruz had invested in an aggressive get-out-the-vote effort, with door-knockers and phone-bankers making tens of thousands of late-race contacts. This is probably the biggest reason Cruz prevailed.

We finished polling Friday night. About a third of Republican caucusgoers, according to the entrance poll reported by CNN, said they had made up their minds within a few days of the caucus. That includes 16 percent who said they did not make up their minds until caucus day — and Florida Sen. Marco Rubio got the plurality of that vote (28 percent), almost doubling the support Trump got with that group (15 percent).[…]

In our polls, Sanders never lost ground from one poll to the next. He won by substantial margins with younger people and with first-time caucusgoers (with obvious overlap between those groups). The CNN entrance poll shows 84 percent of the under-30 crowd stood up for Sanders. This same age group supported Barack Obama in 2008, but with 57 percent of their vote.

Sanders won 59 percent of the first-time caucusgoer vote, not far off the margin we showed in our poll. The surprise was how large that group was Monday night. Our poll suggested it would be around 1 in 3, but it was 44 percent.