Iowans who approve of U.S. Senator Chuck Grassley’s work greatly outnumber those who disapprove, according to the latest poll by Selzer & Co for the Des Moines Register and Mediacom. Selzer conducted the survey between February 21 and 24, when Grassley’s stance against filling the U.S. Supreme Court vacancy was a prominent news topic. Among the 804 Iowa respondents, 57 percent said they approved of the way Grassley is handling his job and 28 percent disapproved.

That approval is down 7 percentage points from a year ago, but it remains well within his normal range over the last several years, Register pollster J. Ann Selzer said. Over the past decade, Grassley has rated as high as 75 percent, in January 2009, and as low as 54 percent, in February 2010.

Public Policy Polling’s last several Iowa surveys have all measured Grassley’s approval at 50 percent or higher, well above his disapproval rating, and showed the senator leading any of his declared Democratic challengers by more than 20 points. PPP surveys in the field last week indicated that GOP senators up for re-election in Ohio and Pennsylvania could be hurt by the refusal even to consider President Barack Obama’s Supreme Court nominee. However, those senators don’t have Grassley’s 36 years of constituent service and traveling the state every year to fall back on.

Whether Grassley’s general election opponent turns out to be Patty Judge or Rob Hogg, Democrats have a long way to go to make this race competitive.

Incidentally, the Selzer poll showed that about a year into Senator Joni Ernst’s tenure, 43 percent of respondents approve of her work, while 31 percent disapprove and 25 percent are not sure. PPP has found similar approval numbers for Ernst in recent months, with disapproval numbers also in the low 40s.

UPDATE: Public Policy Polling released a new Iowa poll on March 4. Grassley’s approval and disapproval numbers were 47 percent and 44 percent, “down considerably from what we usually find for him as he loses crossover support from Democrats because of his intransigence on the Supreme Court issue.” Some 56 percent of all Iowa respondents and 58 percent of independents in the sample “want the Supreme Court vacancy to be filled this year.” In addition, by a 66 percent to 26 percent margin, Iowa respondents “say that the Senate should at least wait and see who’s put forward before deciding whether to confirm or deny that person.” Among independents in the sample, just 24 percent say they would be more likely to vote for Grassley if he refuses to confirm the president’s Supreme Court nominee, 48 percent say they would be less likely to vote for him, and 28 percent say it would make no difference.