1998Final results
1998 election for U.S. Senate in Iowa
U.S. Senate · Iowa
Chuck Grassley (R) won with 68.4% of the vote, defeating David Osterberg (D) by 37.9 points.
Chuck GrassleyRepublican · winner
68.4%648,480
David OsterbergDemocrat
30.5%289,049
Susan MarcusNatural Law
0.8%7,561
Margaret TroweSocialist Workers
0.3%2,542
947,632 votes
Source: MIT Election Data and Science LabUpdated Sep 30, 2026, 7:25 AM ET
The seat over time
D − R margin in this seat's races around 1998
Races before and after
Source: MIT Election Data and Science LabUpdated Sep 30, 2026, 7:25 AM ET
Money in this race
Each line compares the two campaigns on one scale.
David OsterbergChuck Grassley
$165.7K
Raised by the campaign
$3.3M
$165.4K
Spent by the campaign
$2.8M
$225
Cash on hand
$1.6M
Campaign money: FEC, through Dec 31, 1998.
Source: FEC campaign filingsUpdated Dec 31, 1998
The candidates
Chuck Grassley (R)David Osterberg (D)
Also on the ballot: Susan Marcus (Natural Law), 0.8%; Margaret Trowe (Socialist Workers), 0.3%