House · 3 November 2026

CA-18 House 2026

98.5% DZoe Lofgren leads TruthIndex™Safe D

Polymarket: 98.4%
Kalshi: 98.5%
Spread: 0.1 pts
24h: –
7 days: +0.1
Updated: Oct 16, 2026, 1:45 PM ET

Zoe Lofgren, last 60 days

How to read this chart

The green line is the TruthIndex™, the chance of this outcome. It combines the prices on both venues and gives more weight to the venue with more money in its order book. The two thinner lines are Polymarket's and Kalshi's own prices, and the grey band between them shows how far apart the two venues are.

The pale bands behind the lines are the rating zones (Toss-up, Lean, Likely and Safe), so you can see when the race moved from one rating to another. Move along the chart, or use the arrow keys, to read the values for each day.

All outcomes

Outcome	TruthIndex™		Polymarket	Kalshi	Spread	24h
DZoe Lofgren	98.5%		98.4%	98.5%	0.1 pts	–
RShane Lewis	2.1%		2.1%	2.1%	0.0 pts	–

Polymarket Kalshi

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Candidates & Background

Shane Lewis

Republican

Shane Lewis, a Republican and U.S. Marine veteran, faces Democratic incumbent Zoe Lofgren in the 2026 election for California's 18th congressional district after finishing second in the top-two primary.

Full candidate profile →

Zoe Lofgren

Democratic U.S. Representative from California (since 1995)

Zoe Lofgren, a Democrat first elected to the U.S. House in 1994 who now represents California's 18th congressional district, faces Republican Shane Lewis, a U.S. Marine veteran, in her 2026 reelection race.

Born 1947 · San Mateo, California

Full candidate profile →

Margin of victory

Each venue's margin market, shown on its own: the two venues set their ranges differently.

Kalshi158 contracts

California's 18th District margin of victory

Lofgren, 30+ pts		94.0%
Lofgren, 33+ pts		89.8%
Lofgren, 36+ pts		81.5%
Lofgren, 39+ pts		73.0%
Lofgren, 42+ pts		60.5%
Lofgren, 45+ pts		46.0%
Lofgren, 48+ pts		–
Lofgren, 51+ pts		22.0%
Lofgren, 54+ pts		12.0%

Source: Kalshi market

Each venue's market

Polymarket$49.9K traded

Prices which party wins.

Zoe Lofgren: Counted · bid 97.7% / ask 99.2% · $10.0K within 5 pts

This market will resolve according to the party of the candidate who wins the CA-18 congressional district seat in the U.S. House of Representatives in the 2026 midterm elections. The midterm elections will take place on November 3, 2026. A candidate's party will be determined by their ballot-listed or otherwise identifiable affiliation with that party at the time all of the 2026 House elections are conclusively called by this market's resolution sources. A candidate without a ballot-listed affiliation to either the Democrat or Republican parties will be considered a member of one of these parties based on the party with which they most recently expressed their intent to caucus at the time all of the House elections are conclusively called by this market's resolution sources. This market will resolve based on the result of the election as indicated by a consensus of credible reporting. If there is ambiguity, this market will resolve based solely on the official results as reported by the United States government, specifically the Federal Election Commission (https://www.fec.gov/).

Full rules on Polymarket

Kalshi1.4K contracts traded