Question:
4. If the election for U.S. Senate was today, would you vote for … Joni Ernst the Republican, Theresa Greenfield the Democrat, Rick Stewart the Libertarian, or Suzanne Herzog an independent candidate? [NAMES WERE ROTATED] [If UNDECIDED: If you had to vote for one of the following candidates at this moment, who do you lean toward – Joni Ernst or Theresa Greenfield?]

Joni Ernst 48%
Theresa Greenfield 45%
Rick Stewart 2%
Suzanne Herzog 1%
(VOL) No one 1%
(VOL) Undecided 3%

About this Poll
The Monmouth University Poll was sponsored and conducted by the Monmouth University Polling Institute from July 30 to August 3, 2020 with a statewide random sample of 401 Iowa voters drawn from a list of registered voters. This includes 176 contacted by a live interviewer on a landline telephone and 225 contacted by a live interviewer on a cell phone, in English. Monmouth is responsible for all aspects of the survey design, data weighting and analysis. The full sample is weighted for party registration, age, gender, race, education, and region based on state voter registration list information and U.S. Census information (CPS 2018 supplement). Data collection support provided by Braun Research (field) and Aristotle (voter sample). For results based on the full voter sample, one can say with 95% confidence that the error attributable to sampling has a maximum margin of plus or minus 4.9 percentage points (unadjusted for sample design). Sampling error can be larger for sub-groups (see table below). In addition to sampling error, one should bear in mind that question wording and practical difficulties in conducting surveys can introduce error or bias into the findings of opinion polls.