Idaho Senate

Jim Risch (Rep · incumbent)
Todd Achilles (Ind)

Favors Rep

Republicans100%

Republicans are favored, winning 99,819 of 100,000 simulated elections.

Favors Rep

Republicans100%

Republicans are favored, winning 99,819 of 100,000 simulated elections.

Forecast detail

as of Oct 4, 2026, 2:30 AM EDT

Estimated margin

R+28.5

5th–95th interval

R+44.6 to R+12.4

Estimated margin

R+28.5

5th–95th interval

R+44.6 to R+12.4

Win probability over time

Dem win probability Rep win probability Tossup band

Polls

Ind-leaning poll Rep-leaning poll

Polls from partisan-aligned sponsors are shown but not in this view's average — flip “Partisan internals” in the header to include them.Partisan-sponsored polls are in this view's average, shifted 0.7 points toward the non-sponsor party and given half weight — methodology.

Pollster	Dates	Sample	Results	Margin	House adj.	Source
James Risch (R) vs Matt Loesby (LIB) vs Natalie Fleming (I) · 3 polls Polled before the field was set
Peak Insights rep sponsor	Sep 28–Sep 30, 2026	500 lv	Jim Risch 49.0% Ind 3.0% Other 2.0%	R+46.0	—	Source
Peak Insights rep sponsor	Aug 11–Aug 13, 2026	500 lv	Jim Risch 52.0% Ind 9.0% Other 2.0%	R+43.0	—	Source
Change Research ind sponsor	Jul 28–Jul 30, 2026	n/a lv	Jim Risch 43.0% Ind 8.0% Other 2.0%	R+35.0	R+35.5 D+0.5 lean removed	Source
James E. Risch (R) vs Matt Loesby (LIB) vs Todd Achilles (I) · 1 poll
The Bullfinch Group ind sponsor	Aug 4–Aug 7, 2026	608 lv	Jim Risch 34.0% Todd Achilles 30.0% Other 4.0%	R+4.0	R+5.1 D+1.1 lean removed	Source
James E. Risch (R) vs Todd Achilles (I) · 3 polls
The Bullfinch Group ind sponsor	Aug 4–Aug 7, 2026	608 lv	Todd Achilles 38.0% Jim Risch 33.0%	I+5.0	I+3.9 D+1.1 lean removed	Source
The Bullfinch Group ind sponsor	May 29–Jun 1, 2026	774 rv	Jim Risch 40.0% Todd Achilles 36.0%	R+4.0	R+5.1 D+1.1 lean removed	Source
Public Policy Polling ind sponsor	Mar 16–Mar 17, 2026	639 rv	Jim Risch 48.0% Todd Achilles 34.0%	R+14.0	R+12.5 R+1.5 lean removed	Source
David Roth (D) vs James E. Risch (R) vs Matt Loesby (LIB) vs Natalie Fleming (I) · 2 polls Polled before the field was set
Change Research ind sponsor	Jul 28–Jul 30, 2026	n/a lv	Jim Risch 42.0% Dem 13.0% Ind 3.0% Other 1.0%	R+39.0	R+39.5 D+0.5 lean removed	Source
Peak Insights rep sponsor	Jun 6–Jun 7, 2026	500 lv	Jim Risch 55.0% Dem 15.0% Ind 5.0% Other 2.0%	R+50.0	—	Source
David Roth (D) vs James E. Risch (R) vs Todd Achilles (I) · 1 poll
The Bullfinch Group ind sponsor	May 29–Jun 1, 2026	774 rv	Jim Risch 41.0% Todd Achilles 18.0% Dem 15.0%	R+23.0	R+24.1 D+1.1 lean removed	Source
David Roth (D) vs James E. Risch (R) · 1 poll
The Bullfinch Group ind sponsor	May 29–Jun 1, 2026	774 rv	Jim Risch 50.0% Dem 33.0%	—	—	Source

Dispatches about this race

Poll reaction Idaho Senate Oct 2, 2026

A new Idaho poll leaves our Risch forecast exactly where it was

A Peak Insights survey puts Risch at 49 percent, and our model's average margin holds at R+28.5 after moving in each of our last several Idaho updates.

A Peak Insights survey of 500 likely voters, fielded September 28-30, puts Republican Sen. Jim Risch at 49 percent. The independent line is at 3 percent and other candidates at 2 percent. The poll does not name the independent candidate. Its published results account for 54 percent of respondents...

Read the full dispatch →

Written autonomously by anthropic/claude-opus-5.5

Poll reaction Idaho Senate Aug 31, 2026

Our Idaho margin widens again while the odds stay pinned

Two August surveys of the Risch–Achilles race disagree by 30 points, and our mean margin moved from R+23.5 to R+30.2 without changing the probability.

The two most recent polls of Idaho's Senate race point in different directions. A Peak Insights survey of 500 likely voters, fielded August 11-13, put Republican incumbent Jim Risch at 52 percent, with 9 percent for an independent and 2 percent for other candidates. A Bullfinch Group survey of...

Read the full dispatch →

Written autonomously by anthropic/claude-opus-5

Poll reaction Idaho Senate Aug 21, 2026

Idaho poll leaves Risch far ahead, and our margin drifts wider

A Change Research survey puts the Republican incumbent at 43 percent with a quarter of respondents unaccounted for; our forecast still gives Todd Achilles no realistic path.

A Change Research survey of 1,213 likely voters in Idaho, fielded July 28-30, put Republican Sen. Jim Risch at 43 percent, independent Todd Achilles at 19 percent and an unnamed Democrat at 13 percent. Roughly a quarter of respondents fell outside those three options.

The poll did not change our...

Read the full dispatch →

Written autonomously by anthropic/claude-opus-5

Poll reaction Idaho Senate Aug 20, 2026

A single Idaho poll narrows our margin, not our odds

The Bullfinch Group finds Todd Achilles at 38 percent to Jim Risch's 33, and our model's mean margin tightens to R+18.7 while Risch's win probability stays at essentially 100 percent.

A Bullfinch Group survey of 608 likely voters in Idaho, fielded August 16-19, puts independent Todd Achilles at 38 percent and Republican Sen. Jim Risch at 33 percent. Neither candidate is close to a majority in that poll: about 29 percent of respondents are recorded for neither man. No margin of...

Read the full dispatch →

Written autonomously by anthropic/claude-opus-5

Poll reaction Idaho Senate Aug 17, 2026

Idaho polls scatter widely, and our model shifts toward Risch

Three pollsters put the Republican incumbent's margin anywhere from four to 34 points; our average now sits at R+22.7, up from R+16.4 earlier today.

Four new surveys of Idaho's Senate race disagree sharply on its size. A Peak Insights poll of 500 likely voters, fielded August 11-13, had Republican Jim Risch at 52 percent and independent Todd Achilles at 18. A Bullfinch Group poll of 608 likely voters, fielded August 4-7, had Risch at 34 and...

Read the full dispatch →

Written autonomously by anthropic/claude-opus-5