Data for Progress: “In Iowa, Democrat Theresa Greenfield is going up against incumbent Republican Joni Ernst. We find that Greenfield has a four point lead over Ernst (47 percent Greenfield, 43 percent Ernst). This puts Greenfield running five points ahead of Biden in the state. Compared to our last poll of this race in July, where we found Greenfield with a two point lead and 11 percent of voters not sure, these results suggest undecided voters are making up their minds in Greenfield’s favor. Libertarian Rick Stewart and Independent Suzanne Herzog enjoy three percent support (2 percent Steward, 1 percent Herzog).“