House · 2026

California’s 48th District

Marni von Wilpert (D)v.Jim Desmond (R)LEAN D

Open seat, currently Republican. District lines changed since 2024.

Projected margin

D+2.9

Nine in ten outcomes: D+12 to R+6

Chance of winning

69%

Marni von Wilpert

Polls alone

D+0.8

2 polls from 2 pollsters; latest Sep 1. Weight in projection: 71%.

Fundamentals alone

D+7.8

Weight in projection: 29%.

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 House 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+0.8

Partisan leanD+4.1

National environmentD+3.6

Incumbency0.0

Incumbent's last over/under-performance0.0

Fundraising gapR+0.8

Fundamentals estimateD+7.8

Input: partisan lean

D+4.9

Presidential vote relative to the nation, 2024 on this year's lines.

Input: raised from itemized individual donors, through June 30

$881K D · $1.6M R

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

Handicappers, for comparison

Cook: Lean D · Sabato: Lean D · Inside Elections: Tilt D

Not an input to the projection.

Table view

All 2 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	Wilpert	Desmond	As published	Adjusted	Share of average
Aug 27 – Sep 1	SurveyUSA for KGTV-TV (California) \| San Diego Union-Tribune	522 LV	45	42	D+3	D+2.1 moved 0.9 toward R	66%	source
Jul 9–14	Lake Research PartnersDEM.-ALIGNED	500 LV	48	46	D+2	R+1.7 moved 3.7 toward R	34%	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.