The Des Moines Register dropped a hammer on Iowa Democrats this evening with the latest statewide poll by Selzer & Co. The Register’s new poll finds Joni Ernst ahead of Bruce Braley by 51 percent to 44 percent, leading Braley in all four Congressional districts, and winning independent voters by 12 points. The poll looks like an outlier to me, compared to most other surveys that were in the field these past two weeks. No other poll has found Ernst above 50 percent this fall, and no non-partisan poll has found her leading Braley by more than four points. Of the ten other polls in the field during the last two weeks, two found Braley ahead by one point, two found the race tied, two found Ernst ahead by one point, and four found her ahead by margins between two and four points.

On November 5, either Ann Selzer will look like a genius, or a bunch of other pollsters (whose surveys found a close race here) will laugh.

The problem for Democrats is that the Register’s Iowa poll always generates more media coverage than any other poll. Even if this poll turns out to be an outlier, it could depress volunteers during the final days. A good GOTV program can overcome a one-point deficit but not seven points.

The Register’s latest poll found Governor Terry Branstad ahead of Democratic challenger Jack Hatch by 59 percent to 35 percent, one of the biggest leads any poll has found for Branstad. Selzer only polled on two other statewide races. Democratic Attorney General leads challenger Adam Gregg by 50 percent to 39 percent. The secretary of state race looks too close to call, with Republican Paul Pate ahead of Democrat Brad Anderson by 44 percent to 41 percent.

P.S. – There’s still plenty of time to enter Bleeding Heartland’s election prediction contest.

UPDATE: Below I’ve added excerpts from the Register’s analysis of the Selzer poll, along with the Braley campaign’s reaction, calling the Register poll an “outlier.”

SECOND UPDATE: Added more commentary on Senate polling below.

From Jennifer Jacobs’ main report on the poll for the Sunday Des Moines Register:

Here’s what has shaped Ernst’s lead, according to the poll results:

• Although a small plurality of likely voters thinks Braley has more depth on the issues, they like Ernst better than Braley on several character descriptions. They think she better reflects Iowa values, she cares more about people like them, and she’s more of a regular, down-to-earth person.

• Voters find Ernst, who has led Iowa troops in war, to be a reassuring presence on security issues, the poll shows. In the wake of news developments on the Ebola outbreak in West Africa, increasing aggressiveness of Russia and the rise of the Islamic State in the Middle East, more likely voters see Ernst as better equipped than Braley to show leadership and judgment, by at least 9 points on each issue.

• Independent voters are going Ernst’s way, 51 percent to 39 percent.

• The negativity in the race has hurt Braley more than Ernst. Forty-four percent say he has been more negative in campaign ads, compared with 32 percent for Ernst.

• Among several potential mistakes the two candidates have made, the one that stands out is Braley’s seemingly condescending remark about Republican U.S. Sen. Chuck Grassley. […]

The Iowa Poll of 701 likely voters in the 2014 general election was conducted Oct. 28-31 by Selzer & Co. of Des Moines and has a margin of error of plus or minus 3.7 percentage points.

Four percent of likely voters remain undecided. Only 7 percent who have made a choice say they could still be persuaded to vote for another candidate. […]

Interviewers contacted 1,026 Iowans ages 18 or older with randomly selected landline and cellphone numbers supplied by Survey Sampling International. Responses were adjusted by age, sex and congressional district to reflect the general population based on recent census data.

Questions based on the subsample of 701 Iowa likely voters in the 2014 election have a maximum margin of error of plus or minus 3.7 percentage points.

Statement released by Braley’s campaign manager, Sarah Benzing:

With the exception of today’s outlier, every single poll of Iowa voters in the last few days has shown this race to be a dead heat heading into Election Day with clear movement in Bruce’s direction. Our campaign’s modeling of the electorate shows that Bruce is headed to victory on the strength of his clear and significant lead among early voters, the superior Democratic ground efforts that will drive far greater numbers of supporters to the polls, and his strong and consistent lead among independent voters.

While the Ernst campaign knows that this race is tight and is actively preparing for a recount, we plan to win on Tuesday night and our staff and thousands of volunteers are hard at work across the state making sure Bruce’s supporters are hearing from us in the final days and are getting their ballots in.

There has been a clear and consistent trend in our polling and modeling showing Bruce leading significantly among independents and sporadic voters. We know that the more voters we can pull out in the final days, the stronger Bruce’s returns will be on Tuesday night-and we have dedicated substantial resources to a field operation that has already expanded the electorate and will significantly outperform any Republican efforts to get their voters out in the final days.

The campaign’s modeling of the early vote returns show clear signs of strength for Bruce heading into Election Day. With over 420,000 votes in already, not only have more Democrats voted than Republicans, but our models show that Bruce has a significant lead among independents who have voted already and those whose ballots we expect to come back, giving him an advantage of over 15,000 votes so far among this group with that number expected to grow in the final days. Bruce is also leading by 22 points among voters who don’t traditionally vote in midterm elections-a critical group that Democrats are successfully working to turn out.

The early return data shows that while Democrats are dramatically expanding the electorate and bringing in more early votes from voters who didn’t vote in 2010, Republicans are simply pushing their consistent voters to vote early instead of on Election Day. Over 40% of the registered Republicans who have already voted this year voted on Election Day in 2010, meaning that their Election Day numbers are going to be significantly worse this year than in the past. Of the registered Democrats who have voted so far, 20% did not vote in 2010, adding over 32,000 sporadic voters to this year’s election totals heading into the final weekend-and we expect that number to jump significantly in the final days.

Over the last two weeks, Democrats have outpaced Republicans in generating new vote by mail request forms every single day and have brought in over 60,000 new forms from voters who will be supporting Bruce.  Over 25,000 more ballots have been requested by Bruce supporters than Ernst supporters, and we expect our superior ground game to bring those ballots in.

Ballots continue to pour in from Bruce supporters at a recent rate of over 9,000 a day, and this is expected to double in the final days. Over 50% of the outstanding ballots sent to Bruce supporters have been requested in the last two weeks and we expect the vast majority of them to come in over the final days as our staff and volunteers knock on their doors and call them to remind them to vote.  

SECOND UPDATE: Nate Silver reacted to the latest Selzer poll at fivethirtyeight:

In September this year, Selzer’s poll showed a 6 percentage-point lead for the Republican Joni Enrst in the Iowa Senate race, defying others that had shown the race as a tossup. Although an early October Selzer poll showed the Democrat Bruce Braley narrowing his deficit to just 1 point, the final Des Moines Register poll, released Saturday night, has Ernst up 51-44 – a 7-point advantage. Other polls of Iowa show Ernst ahead, on average, by a percentage point or two.

Of course, the polling average is usually a more reliable indicator than even the best polls. No poll is clairvoyant – even one that consistently rates as among the most accurate in the country, as Selzer’s does. Polls face inherent limitations because of sampling error, and even the best pollsters face challenges in getting voters to talk to them. If Ernst’s 7-point lead in Selzer’s poll represented the equivalent of a point spread, the FiveThirtyEight model would take Braley’s side of it.

But the model is increasingly confident that Ernst will win. Her chances are improved to 71 percent, up from 62 percent before the Des Moines Register poll. That’s about as large a swing as you’re likely to see on the basis of a single survey, at least in a densely polled state such as Iowa.

This poll, in other words, is a big deal. Just as Ernst’s chances have surpassed 70 percent for the first time, so have the GOP’s chances of taking over the Senate, which are now 72 percent. This is not coincidental: Iowa is a pivot point in the Senate calculus, and the two numbers have closely tracked each other for much of the year.

I didn’t see anything in the Des Moines Register’s write-up about the “likely voter” screen Selzer uses. On October 30, Nate Cohn discussed several reasons “Why Polls Tend to Undercount Democrats”:

But the reasons to think that today’s polls underestimate Democrats are not based on just the last few years of results. They are also based on a fairly diverse set of methodological arguments, supported by extensive research, suggesting that many of today’s polls struggle to reach Democratic-leaning groups.

“The problems that we’re having with getting representative samples tend to lead us toward people who tend not to be Democrats,” said Scott Keeter, the director of survey research at the Pew Research Center. The most highly regarded pollsters, like those at Pew, have made many adjustments to compensate. But other polls, including many of those informing polling averages and Senate forecasting models, are not nearly as high in quality. Another highly regarded pollster, who requested anonymity, put it more bluntly, calling the new challenges “scary.” Many pollsters are reluctant to say things on the record that might undermine confidence in their own polling; others are unwilling to say anything at all, even to offer basic methodological information.

There are reasons to question whether the problems will be as acute this year, because many of the young and nonwhite voters who pose the biggest challenges to pollsters will most likely stay home in a midterm election. Even if the polls are again biased toward Republicans this year, there are reasons to doubt whether Democrats will retain control of the Senate. The Republicans might have a large enough advantage to withstand another round of modest polling errors.

But the larger concerns will remain, and they might be more significant in 2016 – when younger and nonwhite people are expected to vote in larger numbers.