2020Final results
2020 election for U.S. Senate in Iowa
U.S. Senate · Iowa
Joni Ernst (R) won with 51.7% of the vote, defeating Theresa Greenfield (D) by 6.6 points.
Joni ErnstRepublican · winner
51.7%864,997
Theresa GreenfieldDemocrat
45.2%754,859
Rick StewartLibertarian
2.2%36,961
Suzanne HerzogOther party
0.8%13,800
1,671,828 votes
Source: MIT Election Data and Science LabUpdated Oct 1, 2026, 10:09 AM ET
The seat over time
D − R margin in this seat's races around 2020
Races before and after
Source: MIT Election Data and Science LabUpdated Oct 1, 2026, 10:09 AM ET
Money in this race
Each line compares the two campaigns on one scale.
Theresa GreenfieldJoni Ernst
$56.4M
Raised by the campaign
$27.7M
$56.3M
Spent by the campaign
$28.5M
$30.2K
Cash on hand
$528.4K
Other candidates' campaigns: Suzanne Herzog $18.3K · Rick Stewart $8.8K.
Campaign money: FEC, through Dec 31, 2020.
Source: FEC campaign filingsUpdated Dec 31, 2020
The candidates
Joni Ernst (R)Theresa Greenfield (D)
Also on the ballot: Rick Stewart (Libertarian), 2.2%; Suzanne Herzog (Other party), 0.8%