In Iowa, Republican President Donald Trump and Republican Sen. Joni Ernst are leading, but their races for re-election are within the margin of error in a new poll of registered voters.

Both the presidential and U.S. Senate race are essentially up for grabs, Monmouth University found in a live poll of 401 registered voters July 30 to Aug. 3.

In the presidential race, Trump is leading Democratic former Vice President Joe Biden, 48 percent to 45 percent, with 3 percent supporting Libertarian Jo Jorgensen and 3 percent undecided. The polls margin of error is 4.9 percent plus or minus.

Iowa looks to be more competitive than four years ago, said Patrick Murray, director of the independent Monmouth University Polling Institute in New Jersey. There is a lot of parity between Trump and Biden in both the strength of their support and the preferences of key demographic groups.

Trump won Iowa by 9 percentage points in 2016.

Although Trump leads statewide, Biden has the edge in 13 swing counties, including Linn, where the 2016 vote margin between Trump and Democrat Hillary Clinton was less than 10 percent. Biden has a 52 percent to 45 percent lead in those counties, which Clinton carried by a combined 1 percentage point margin.

In Johnson, Polk and Story, which Clinton carried by 17 points, Biden has a 62 percent to 31 percent lead in the Monmouth poll.

Trump has a 59 percent to 34 percent lead in counties he won by a combined 30 points four years ago.

Trump has a 51 percent to 41 percent advantage among white voters without college degrees. Biden leads among white voters with college degrees, 48 percent to 46 percent.

The race remains tight when different likely voter models are applied.

A model based on a higher turnout than 2016 puts the race at 48 percent Trump and 46 percent Biden.

A model reflecting lower voter turnout produces a similar 47 percent Trump and 47 percent Biden result.

Republicans (36 percent) are somewhat more likely than Democrats (28 percent) to feel very optimistic about the 2020 presidential election. But a larger number of Democrats (46 percent) than Republicans (34 percent) say they are more enthusiastic about voting this year compared to past elections.

One of the reasons Biden may do nominally better in a lower turnout scenario is that his voters are slightly more motivated, Murray said. Its not a statistically significant difference, though, and this race is currently up for grabs, no matter how you slice it.

Both Biden and Trump are upside down in favorability ratings.

While 45 percent have a favorable opinion of Trump, 50 percent have an unfavorable opinion. Bidens rating is 43 percent favorable against 49 percent unfavorable.

In the Senate race, unlike previous polls, Ernst, who is seeking re-election to a second term, is leading her Democratic challenger, Theresa Greenfield, by the same margin 48 percent to 45 percent.

Libertarian Rick Stewart gets support from 2 percent; independent Suzanne Herzog, 1 percent; and undecided, 3 percent.

When likely voters are asked, the race gets tighter, with Ernst leading 48 percent to 47 percent, according to Monmouth.

Previous polls over the spring and summer have shown a tight Senate race. The polls produced margins similar to Monmouths, but with Greenfield holding a lead within the margin of error.

Ernst won a competitive open seat contest six years ago. Greenfield is giving the incumbent a run for her money to hold onto it, Murray said.

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According to FiveThirtyEight.coms rating of pollsters, the Monmouth poll earned an A-plus with a slight Democratic bias.

The poll also found 40 percent of Iowa voters say it is very likely they will vote by mail rather than in person in the Nov. 3 election. Another 1 percent are somewhat likely to do this, 12 percent are not too likely, and 30 percent are not at all likely.

In many Iowa counties, active voters will receive an absentee ballot application for the 2020 general election. Just 20 percent reported they had regularly voted by mail in past elections.

Comments: (319) 398-8375; james.lynch@thegazette.com

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Donald Trump, Joni Ernst have slight leads in poll of Iowa voters - The Gazette