1998 United States Senate election in Iowa

1998 United States Senate election in Iowa

←  1992 November 3, 1998 2004  →

Nominee Chuck Grassley David Osterberg Party Republican Democratic Popular vote 648,480 289,049 Percentage 68.41% 30.49%

County results Grassley:     50-60%     60-70%     70-80%     80-90%     >90%

U.S. senator before election Chuck Grassley Republican Elected U.S. Senator Chuck Grassley Republican

The 1998 United States Senate election in Iowa was held November 3, 1998. Incumbent Republican United States Senator Chuck Grassley sought re-election to a fourth term in the United States Senate, running against former State Representative David Osterberg, who won the Democratic nomination unopposed. Grassley had not faced a competitive election since 1980; this year proved no different, and Grassley defeated Osterberg in a landslide.

Democratic primary

Candidates

• David Osterberg, former State Representative

Results

Democratic primary results ^[1]

Party		Candidate	Votes	%
	Democratic	David Osterberg	86,064	99.45%
	Democratic	Write-ins	476	0.55%
Total votes			86,540	100.00%

Republican primary

Candidates

• Chuck Grassley, incumbent United States Senator

Results

Republican primary results ^[1]

Party		Candidate	Votes	%
	Republican	Chuck Grassley (Incumbent)	149,943	99.72%
	Republican	Write-ins	419	0.28%
Total votes			150,362	100.00%

General election

Debate

1998 Iowa United States Senate election debate

No.	Date	Host	Moderator	Link	Republican	Democratic
Key:  P Participant  A Absent  N Not invited  I Invited  W  Withdrawn
					Chuck Grassley	David Osterberg
1	Oct. 19, 1998	Iowa Public Television	Dean Borg	C-SPAN	P	P

Polling

Poll source	Date(s) administered	Sample size [a]	Margin of error	Chuck Grassley (R)	David Osterberg (D)	Undecided
Mason Dixon [2]	October 25–27, 1998	803 (LV)	± 3.5%	68%	24%	8%
Mason Dixon [2]	October 11–13, 1998	809 (LV)	± 3.5%	67%	22%	11%
Mason Dixon [2]	September 12–14, 1998	804 (LV)	± 3.5%	69%	19%	12%
Mason Dixon [2]	July 18–21, 1998	834 (LV)	± 3.5%	68%	17%	15%
Selzer & Company [2]	June 20–24, 1998	581 (LV)	± 4.0%	72%	18%	10%

Results

United States Senate election in Iowa, 1998 ^[3]

Party		Candidate	Votes	%	±%
	Republican	Chuck Grassley (Incumbent)	648,480	68.41%	−1.20%
	Democratic	David Osterberg	289,049	30.49%	+3.29%
	Natural Law	Susan Marcus	7,561	0.80%	−0.47%
	Socialist Workers	Margaret Trowe	2,542	0.27%	+0.16%
	Write-ins		275	0.03%
Majority			359,431	37.92%	−4.50%
Turnout			947,907
	Republican hold		Swing

See also

• 1998 United States Senate elections

Notes

1. Key:
   A – all adults
   RV – registered voters
   LV – likely voters
   V – unclear

References

1. "Results" (PDF). sos.iowa.gov. 1998. Retrieved October 15, 2019.
2. "CNN AllPolitics Election '98 - Iowa 1998 Polls". CNN. Archived from the original on June 25, 2025. Retrieved June 25, 2025.
3. "Election info" (PDF). clerk.house.gov. 1998. Retrieved October 15, 2019.