Iowa · U.S. Senate

How this state voted, 2024 −13.260 points

The state's presidential margin in 2024 as a share of all votes cast, from our own county sums — the same measurement the model's statewide terrain center is built from. Every pull below is measured from here, not from EVEN, which is why a landslide seat's listed pulls are small numbers and still land where the forecast does.

• 2024 presidential result for this state, as a share of all votes cast, from Call the Map's own county sums.
• Same source as Act I's 2024-president reference mark, so the origin lands on it.

Fitted model, above the terrain shown +9.638 points

What the fitted model adds on top of the starting terrain above — incumbency, past results, campaign finance and the other fitted terms — measured from that terrain rather than from EVEN. It is a comparison with the starting point already shown, not a separate input. The source detail lists the variables the fit uses.

• Fitted baseline -3.622 minus starting point -13.260 = 9.638 points.
• For orientation, the presidential results here: 2024 R+13.3, 2020 R+8.2.
• The work: the −3.6 D fundamentals push is the sum of the dynamic formula's surviving variables for this race — each one's own contribution is listed below.
• fundamentals core = 25-term dynamic formula (mass fit over the master feature matrix, held-out-cycle validated; see matrix/feature_dictionary.md + mass_fit_report.json)
• 9-term formula, held-out validated.

National environment +3.197 points

The contribution to this race’s margin, not the national polling margin itself. The race’s loading, reference level and polling blend determine how much of the national climate reaches its final forecast.

• Three-source blend, updated 2026-10-14: 53% generic-ballot aggregates (D+7.7) · 28% special-election overperformance (D+9.0 across 46 specials) · 20% approval-implied (D+9.1 from net approval -24.3).
• Latest polls — generic ballot 2026-10-14 (14 days old), approval 2026-10-14 (14 days old).
• Generic-ballot average D+7.7 · support factor 0.87 (the share of that channel's capacity the admitted polls carry) — separate inputs; their product is a capacity diagnostic, not a margin.
• Weights are the 55/25/20 capacities scaled by each channel's evidence and renormalized, so thin polling widens the interval instead of pulling the center toward zero — 12% of the weight is carried that way.
• Blended national environment: D+8.3.
• Applied at full strength to this chamber's races.
• This step’s recorded contribution to the margin is +3.2 D.
• Blended national environment: D+8.3 (updated 2026-10-14).
• Effective poll weight 88%; fundamentals share 12%, carried by the interval (×1.06) rather than by the center.
• The support factor is the share of the generic-ballot capacity the admitted polls carry; average × support is a capacity diagnostic, not a margin, and is not what the row above multiplies.
• Applied at full strength to this chamber: +3.2 of this margin.

This race’s polls −0.509 points

What this race’s own recent polling adds beyond its prior. The forecast weights each poll for recency and sample size and counts each pollster once; the weights listed here are those of the polls’ own average.

• Echelon Insights (2026-10-23, n=403): D+2.0 · weight 0.52 in the poll average
• InsiderAdvantage (2026-10-22, n=1,200): R+1.5 · weight 0.88 in the poll average
• co/efficient (2026-10-19, n=863): R+3.0 · weight 0.72 in the poll average
• Trafalgar Group (2026-10-15, n=1,094): R+1.7 · weight 0.77 in the poll average
• New River Strategies/GS Strategy Group (2026-10-13, n=602): D+2.0 · weight 0.56 in the poll average
• National Public Affairs (2026-10-12, n=678): R+1.0 · weight 0.59 in the poll average
• … and 29 more below.
• Poll average D+0.5, from 35 polls · 35 recorded polls. This is the polls’ own average, each poll at its published margin, the figure this page’s poll summary shows. In Senate races the forecast then counts a poll sponsored by a party or campaign at a quarter of its weight and moves its margin 2 points against that party, which puts the average it reads at D+0.6. It then applies a fitted correction of 1.6 points toward Republicans for Senate races, measured from past polling error, before blending it with its other evidence. The forecast gives the polls 98% of the weight against its structural prior for this race, which moves the margin 0.5 points toward Republicans from where it stood before the polls. Eligible polls: latest poll: 2026-10-23 (5 days old).

Structural safeguards −0.018 points

Bounded corrections that keep the model consistent with structural facts.

• Applied only when a safe state's dynamic fundamentals point in the same direction as its strong presidential lean but are materially compressed toward zero.
• The 25% correction toward that lean improved safe-race MAE in strict expanding-window validation without changing a historical call.
• The disclosed adjustment is −0.0 D.

Votes for other candidates +0.032 points

Every step above is measured between the two major-party candidates alone, as if nobody else were on the ballot. The forecast sets 3.4% of the vote aside for other candidates and write-ins, so as a share of every vote cast the gap between the two is smaller by that much. This step is exactly that: the two-party margin times the share going to other candidates. It is the same arithmetic that turns the two-party margin into the two shares printed at the top of the page.