Races · house · 2026 · Massachusetts

house · open seat

Massachusetts house

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Safe DD +33.4 forecast · 3 months 27 days to election· 0 polls · 2 marketsMarkets 11h agoRating today

Live model · win probabilityupdated 11h ago · poliagg-v34
99% Clark (D)
1% (R)
Win probability
Katherine Clark99% (D)
Republican1% (R)
Modelupdated 11h ago · poliagg-v34
Chance of winning across many simulations of the race — not projected vote share.
R+15R+5TIEDD+5D+15
Predicted margin
Point estimateD +33.4
80% CID+17.3 → D+49.5
The model’s central margin (D-positive) with its 80% interval — the shaded band on the scale.
Predicted final margin D +33.4 · 80% CI D+17.3 → D+49.5 · 3 months 27 days to election

Momentum

—

insufficient data

Tipping-point P

3.8%

Decisive for chamber control

Market · D-side

D 94¢

Cross-platform consensus

News articles · 30d

—

no recent coverage

Where this race stands

Verified

Safe D · model 99% D

No recent polls or markets for this race. PVI baseline (D+24) suggests Safe D.

The poliagg-v34 ensemble forecasts D+33.4 with an 80% CI ranging from D+17.3 (10th pctile) to D+49.5 (90th pctile), giving D a 99% chance of winning.

Tipping-point probability: 3.8% of simulations see this race as decisive for chamber control.

CITATIONS · safe-d · low-tipping

Forecast · poliagg-v34

Predicted final margin

D +33.4

80% CI: D +17.3 → D +49.5 · win prob 99%

R+60R+30TIEDD+30D+60

Quality · inputs

Data quality · medium

Polls used	0
Days to election	118
Residual σ	12.56pt
Generated	7/7/2026

▼ Compare with other models2 models

qgbt-v1GBT (qgbt)

D +47.1

80% CI D +7.6 → D +56.7

CV MAE 8.51

consensusMarket-implied

D +15.1

no interval

market-implied

Prediction markets

Consensus · D 94¢1 platformupdated 11h ago

Cross-platform price · history

80¢90¢100¢54 DAYS · D YES PRICENOWMay 14Jul 7

Per-platform · current

Platform	D YES	R YES	7d Δ	Vol	vs cons
Polymarket “Will the Democratic Party win the MA-05 House seat?”	94¢	4¢	+0¢	—	+0

Endorsements · 10 total

Source · Wikipedia · 0 candidates with no endorsements yet

10Clark · 100%
Endorsements tracked
Katherine Clark10 · 100%
Republican0 · 0%
Total10
Scraped from each candidate’s Wikipedia endorsement list.

DKatherine Clark10 endorsers

Most notable · AIPAC

Organizations10

Money raised · own committees

FEC Schedule E (independent expenditures) + candidate-committee totals · last filing —

Katherine ClarkOWN COMMITTEE

Receipts

$3.4M

Disburse

$2.8M

Cash on hand

$2.0M

Debts

Top industries

No industry data.

Top contributors

No contributor data.

Editorial ratings · 4 raters

Cook · Sabato · Inside Elections · 538 · DDHQ et al.

Safe D4

Cook Political Report

Safe D

Jun 17

Inside Elections

Safe D

Jun 24

Sabato's Crystal Ball

Safe D

Jun 8

Split Ticket

Safe D

Jun 24

Demographic crosstabs

age · education · race · gender

No demographic crosstabs published for this race yet. Most pollsters release only topline numbers; subgroup breakdowns (age, education, race, gender) appear here when a pollster publishes them.

Rating timeline

May 5, 2026Safe Dmodel

May 3, 2026Lean Dmodel

Verification trail

Polls verified0 / 0deterministic

Polls flagged—none

Markets ingested1 platformupdated 11h ago

FEC filingssyncedcommittee + IE

Endorsements10 totalWikipedia scrape

News coverage< 5 articlesGoogle News

Method · bounds + percentage totals + date-order checks