Maine's 2026 U.S. Senate race is the most consequential Republican-held seat on the board — the only GOP senator in a state Kamala Harris won in 2024. Susan Collins (R) faces a competitive Democratic primary on June 9 between insurgent oyster farmer Graham Platner (leading 55%–28%) and two-term Governor Janet Mills. The winner faces Collins in November in a race that could determine Senate control. Both Democratic candidates lead Collins in general election polling.
The Maine Senate race is simultaneously two races: a contested Democratic primary between two candidates representing fundamentally different theories of the Democratic Party — an anti-establishment populist (Platner) vs. a vetted institutional executive (Mills) — and a general election against the most vulnerable Republican senator in the country.
Collins's approval numbers are historically bad: 57% unfavorable statewide and 30 points underwater with independents (Emerson, March 2026). She is betting on her Appropriations record, occasional bipartisan votes (she was one of three Republicans to vote against the Big Beautiful Bill), and the strength of the Pine Tree Results PAC ($5.6M+ raised, targeting $12M) to survive a wave environment.
Graham Platner — Oyster farmer, Marine/Army vet · Score: 38% ✅ · Primary: 55%
Janet Mills — 2-term Governor, former AG/DA · Score: 61% ✅ · Primary: 28%
David Costello — Brunswick, 2024 Senate nominee · Score: 52% · Primary: 4%
Ranked-choice voting · June 9 primary
Susan Collins — 5-term incumbent · Score: 38% · General: 41-43%
Only Republican senator in a Harris state · 57% unfavorable statewide · AIPAC ~20% of 2025 fundraising
Graham Platner carries documented controversies that PoliVion scores under ip_ped:15. The Bangor Daily News unearthed 2013 Reddit posts in which Platner wrote that women concerned about rape should "not get so f***ed up they wind up having sex with someone they don't mean to" and "act like an adult for f***s sake." He has apologized for these posts, attributing them to PTSD and post-combat disillusionment. A tattoo resembling the Nazi SS Totenkopf was revealed via video; Platner said he got it while drunk in Croatia and didn't recognize the symbol. He has had it covered and apologized. In February 2026, he retweeted a clip from Stew Peters, a white supremacist, which was deleted hours later (campaign said they were unaware of Peters's views). He also appeared on a YouTube channel whose host has spread antisemitic claims.
PoliVion applies ip_ped:15 for the Reddit posts — specifically the minimization of sexual violence, which is documented, sourced, and admitted. The tattoo and social media incidents raise additional concerns but are factored into the overall governance competence score. Despite these controversies, Platner leads the primary 55–28 in the latest independent polling, suggesting the Democratic base has largely absorbed this information and continued to support him.
Zeteo reported in February 2026 that AIPAC accounted for approximately 20% of Susan Collins's 2025 fundraising — the highest documented Israel lobby proportion of any 2026 Senate candidate. Collins has a documented AIPAC meeting page on her Senate website and has cosponsored bipartisan pro-Israel resolutions. PoliVion applies ip_foreign:25, which floors her Donor Independence score to 44/100.
| Candidate | Status | Lobby Exposure | Notes |
|---|---|---|---|
| Susan Collins (R) | ⚠ Documented | ~20% of 2025 fundraising (~$900K+) | Highest documented Israel lobby proportion of any 2026 Senate candidate. ip_foreign:25 applied. |
| Graham Platner (D) | ✓ Not Listed · Pledged $0 | $0 documented | Pledged to refuse AIPAC and any group supporting the Gaza genocide. |
| Janet Mills (D) | ⚠ Israel First | Not quantified | Listed as "Israel First" on TrackAIPAC candidates page. Multiple posts citing pro-Israel positions. No FEC dollar amounts (gubernatorial candidate). ip_foreign:8 applied. |
| David Costello (D) | ✓ Not Listed | $0 documented | Not listed. Minimal campaign infrastructure. |
Sources: TrackAIPAC.com · Zeteo, "Susan Collins Is Getting More Money From AIPAC Than Small Donors," February 4, 2026 · Checked March 29, 2026.
Maine's 2026 U.S. Senate race features a Democratic primary on June 9, 2026 using ranked-choice voting to determine who will challenge five-term Republican incumbent Susan Collins in November.
The two main Democratic candidates are Graham Platner (oyster farmer and Marine/Army veteran, leading at 55% in primary polling) and former two-term Governor Janet Mills (28% in primary polling).
Maine uses ranked-choice voting for its primary election. The primary is June 9, 2026, and the winner advances to face Susan Collins in the November 3 general election.
Collins's approval numbers are historically unfavorable — 57% unfavorable statewide and 30 points underwater with independents (Emerson, March 2026). She is being outspent and faces a competitive general election.