House District Hillsborough 15

Forecast

Held today

0 D, 2 R

On the ballot

2 Democrats, 2 Republicans for 2 seats

District party margin

R+4.6 (90% range R+15.6 to D+6.3)

Chance Democrats gain seats here

34%

Chance Democrats lose seats here

0%

Rating (seat share)

Lean R

Seat split distribution

Candidates

Candidate	Party	Win chance
Mark McLean (incumbent)	R	79%
Mark Proulx (incumbent)	R	79%
Michael Farley	D	21%
Michael Fitzell	D	21%

How the forecast was built

Statewide generic legislative margin (environment)	D+2.9
+ District partisan lean	-7.5
= Expected party margin (mean Democratic candidate vs mean Republican candidate)	R+4.6

Each candidate's share is the party's share plus 2.5 points if an incumbent, plus a candidate-specific draw (SD 3.5 points, estimated from how far same-party candidates finished apart in 2022 and 2024). The district margin itself carries statewide, regional and district error (district SD 5.0 pts). The top 2 by share win. Independents are placed with the weaker major party minus a 6.0-point penalty.

Partisan lean (exact by town)

Race	District	Statewide	Lean	Weight
2024 President	R+3.7	D+2.8	-6.5	0.4
2024 Governor	R+18.5	R+9.5	-9.0	0.15
2022 U.S. Senate	D+1.8	D+9.3	-7.5	0.2
2022 Governor	R+29.7	R+15.8	-14.0	0.1
2020 President	D+0.4	D+7.4	-7.0	0.15

Last House result (2024): party margin R+11.8 vs a statewide legislative environment of R+2.6, incumbency removed (+2.5) → lean -6.7, blended at 30%.

Past results in this district

2024 — D 0, R 2 of 2 · party margin R+11.8

R Mark McLean (i)	2,656	✓
R Mark Proulx (i)	2,605	✓
D Thomas Katsiantonis	2,092
D Lara Quiroga	2,057

2022 — D 0, R 2 of 2 · party margin R+9.0

R Proulx	2,011	✓
R McLean (i)	1,946	✓
D Lemay	1,678
D Quiroga	1,627