U.S. Senator Chuck Grassley has only a 48 approval rating among Iowa voters and leads Democratic challenger Patty Judge by only 48 percent to 41 percent, according to a new survey by Public Policy Polling. The firm robo-polled 630 Iowa voters on June 9 and 10, producing a margin of error of plus or minus 3.9 percentage points.

By way of comparison, a PPP survey taken in early June 2010 showed Grassley leading Democratic candidate Roxanne Conlin by 57 percent to 31 percent. In fact, the only 2010 poll that showed Grassley below 50 percent against Conlin was by Research 2000, a firm later discredited after analysts found “extreme anomalies” in its survey results.

Democrats will be encouraged by other findings from today’s PPP polling memo:

-Grassley leads Democratic challenger Patty Judge just 48-41. The candidates are knotted with independents at 40%, and Judge has a 48/44 advantage with women.
-After years of approval ratings over 50%, Grassley continues to find himself with less than half of voters giving him good marks in the wake of voter unhappiness about his handling of the Supreme Court vacancy. Only 48% of voters approve of the job he’s doing to 41% who disapprove, including an upside down 42/50 spread with independents. His personal favorability rating is below 50% as well, at 49/42.
-Patty Judge has more room to grow. 12% of Democrats are undecided, compared to only 2% of Republicans. And while Grassley has near universal name recognition already, Judge is currently known to only 66% of voters in the state. Judge actually leads Grassley 49/45 among voters who are familiar with her.

I eagerly await the next poll of the U.S. Senate race by Selzer & Co for the Des Moines Register. In February, Selzer measured Grassley’s approval rating at 57 percent, amid widepsread media coverage of Senate Republicans vowing not to consider any successor to Supreme Court Justice Antonin Scalia this year. Grassley’s approval rating has not dropped below 54 percent in any Selzer poll taken in the past ten years.

Today’s PPP poll was commissioned by the Constitutional Responsibility Project, which supports filling the Supreme Court vacancy. In early March, a PPP survey conducted on behalf of Americans United for Change found Grassley at 47 percent approval/44 percent disapproval–considerably lower numbers than Selzer’s poll had found less than two weeks before. PPP had previously measured Grassley’s approval rating at 52 percent in August 2015, 50 percent last November, and 53 percent last December.

An April survey by Hart Research Associates found Grassley’s favorability rating at only 42 percent among Iowa voters. But that poll appeared to have “primed” respondents to evaluate the senator by his stand on the Supreme Court controversy. The latest PPP survey asked about Grassley, Judge, and the IA-Sen race without any issue-based questions.

UPDATE: Added below the Republican Party of Iowa’s response to this poll. I should have mentioned that Public Policy Polling conducted some internal polling for Judge’s campaign before the primary. This Federal Election Commission report lists a $2,500 disbursement to PPP on April 16.

An Iowa GOP press release of June 16 alleged that PPP had “fabricated” numbers.

Patty’s Polling Problem: New fabricated poll fails to boost her numbers, shows improved standing for Grassley

(DES MOINES) – While the DSCC is touting a new poll that shows their hand-picked candidate struggling to gain traction after they had to mightily pull her over the finish line in this month’s primary, the numbers paint a polling problem for Patty.

First, let’s get to the elephant in the room. According to her FEC report, PPP is the Judge campaign’s pollster:

Now, let’s get to their turnout model:

2012 actual Iowa general election turnout:
Democrat: 33.5%
Republican: 34.8%
Independent: 31.7%

PPP 2016 turnout model (Q 11):
Democrat: 37%
Republican: 35%
Independent: 28%

Even when they skew the model by increasing Democratic turnout and limiting independents, they still can’t get her over the top.

Finally, by PPP’s own account, Chuck Grassley’s approval numbers in Iowa have actually improved:

March 4, 2016:
Approve: 47%
Disapprove: 44%

June 9-10, 2016:
Approve: 48%
Disapprove: 41%

“Patty Judge can cook up all the phony poll numbers she wants, but the fact remains she is hiding from Iowans and is finding it terribly difficult to find real support,” said Republican Party of Iowa Chair Jeff Kaufmann. “Patty Judge says Iowans can’t ignore her, and she’s right – you can’t ignore something that isn’t there.”​

I see no basis for accusing PPP of “fabricating” poll numbers. You can criticize their modeling of the electorate, but that inevitably involves some guesswork. Grassley’s approval moving from 47 percent in March to 48 percent in June is not statistically significant.

As I said above, I eagerly await the next Des Moines Register poll of this race. Though Selzer’s polls are not always on target, I trust an independent poll conducted for a media organization more than a poll conducted on behalf of an advocacy group with a stake in the race.