Senate · 2026

Kansas Senate

Adam Hamilton (D)v.Roger Marshall (R)LEAN R

Incumbent: Roger Marshall, currently Republican.

Projected margin

R+4.6

Nine in ten outcomes: D+4 to R+14

Chance of winning

80%

Roger Marshall

Polls alone

R+2.5

6 polls from 6 pollsters; latest Sep 16. Weight in projection: 51%.

Fundamentals alone

R+6.8

Weight in projection: 49%.

Polls

The average over time

Each poll is first shifted by its sponsor's and its pollster's measured lean, then weighted by recency and track record. Sample size gets no weight: in 2,000-plus past races it predicted nothing about accuracy. Why.

adjusted weighted average shading: which side the average favors each poll, as published party-aligned pollster or sponsor

Before any poll

What the fundamentals say

A regression on past Senate races, fit without looking at this year. The national environment term uses the generic ballot after its historical correction (D+5.3).

What each term adds to the estimate

BaselineD+0.5

Partisan leanR+10.9

National environmentD+3.3

IncumbencyR+1.8

Incumbent's last over/under-performanceD+1.3

Fundraising gapD+0.8

Fundamentals estimateR+6.8

Input: partisan lean

R+14.6

Presidential vote relative to the nation, 2024 (and 2020).

Input: raised from itemized individual donors, through June 30

$3.0M D · $1.8M R

FEC filings; the model uses the log of the ratio.

Handicappers, for comparison

Cook: Likely R · Sabato: Likely R · Inside Elections: Likely R

Not an input to the projection.

Table view

All 6 polls in the average

“Share” is how much of today’s average each poll supplies. It depends on recency, the pollster’s record, whether the poll screens for likely voters, and how many other polls the same firm has in the race. It does not depend on sample size.

Dates	Pollster	Sample	Hamilton	Marshall	As published	Adjusted	Share of average
Sep 15–16	Emerson College for Nexstar	750 LV	44.8	43.3	D+1	D+1.4	32%	source
Sep 8–10	co/efficient	915 LV	44	49	R+5	R+4.1 moved 0.9 toward D	23%	source
Aug 12–16	Global Strategy GroupDEM.-ALIGNED for People Over Politics Action Fund	800 LV	44	43	D+1	R+2.7 moved 3.7 toward R	21%	source
Aug 7–8	Public Policy PollingDEM.-ALIGNED for Senate Majority PAC	569 RV	45	46	R+1	R+4.5 moved 3.5 toward R	11%	source
Jul 8–13	GBAODEM.-ALIGNED for Hamilton's campaign	600 LV	43	47	R+4	R+7.3 moved 3.3 toward R	13%	source
Jan 26–28	Tavern Research	1,013 LV	46	54	R+8	R+7.7 moved 0.3 toward D	1.5%	source

LV: likely voters. RV: registered voters. A: all adults. “Adjusted” is the published margin after removing the sponsor shift and the pollster’s measured house effect; the small print says how far that moved the poll. Dem.-aligned and Rep.-aligned mark polls paid for by a party, a campaign, or an allied group, or taken by a firm whose published work is mostly for one side. They are shifted by the average lean of such polls, then counted at full weight.

History

Recent results for this office

Year	Democrat	Republican	Result
2022	Mark R. Holland	Jerry Moran	R+23.0
2020	Barbara Goolsbee Bollier	Roger Marshall	R+11.4
2016	Patrick Wiesner	Jerry Moran	R+29.9
2014	Gregory Orman (I)	Pat Roberts	R+10.6