Maine Democratic primary voters are deciding the party’s Senate nomination on June 9, 2026, with Graham Platner, an oyster farmer and Marine Corps veteran, widely expected to secure the designation and set up a closely watched general election against Republican incumbent Susan Collins.
Platner, born September 1, 1984, is a lifelong Maine resident who operates an oyster farm and has served as chair of the Sullivan Planning Board. His rise from political obscurity to presumptive Democratic nominee has drawn national attention, particularly among the party’s progressive wing, which has backed his candidacy despite recent controversies surrounding his past.
The primary was dramatically reshaped in late April when Maine Gov. Janet Mills suspended her campaign, citing a lack of funds to compete against Platner’s grassroots momentum. Mills had struggled to outshine the first-time candidate despite her statewide office. Although Mills officially suspended her campaign, she remained on the June 9 ballot because state law requires a withdrawal notice at least 70 days before the primary—a deadline that had already passed. Voters could still cast ballots for her, though her campaign was inactive.
Platner faces minor opposition from Democratic longshots David Costello and Andrea LaFlamme on the primary ballot. His path to the nomination has been straightforward since Mills’ exit, and multiple sources indicated he held a commanding lead heading into voting day.
If Platner wins the primary, he will advance to November 2026 to face Collins in one of the most anticipated Senate races of the year. Recent polling shows Platner performing competitively against the three-term incumbent. A University of New Hampshire poll from May 27, 2026, found that 51% of likely general election voters would support Platner against Collins. A separate survey from UMass Lowell, released June 4, showed Platner holding a slight lead over Collins in a general election matchup. Real Clear Polling’s aggregate of recent surveys gives Platner a +7.4-point advantage, with him at 48.7% and Collins at 41.3%.
Platner’s campaign has centered on working-class themes and criticism of wealthy interests. He has received endorsements from progressive organizations including the Working Families Party and Common Defense, a veterans advocacy group. However, his campaign faced setbacks in recent months as reports emerged about his past, including allegations of violent rhetoric in since-deleted online posts from years earlier, which he disavowed. The Washington Post reported that these revelations had led some Democrats to worry about his viability and consider whether Mills might revive her candidacy—concerns Mills herself did not act on.
Sources
- The New York Times — Live primary results and reporting that Platner is widely expected to win the Democratic primary
- PBS — Reporting on Platner seeking the Democratic nomination and setting up a critical race with Collins
- University of New Hampshire Survey Center — Poll showing 51% of voters would support Platner against Collins in general election (May 27, 2026)
- UMass Lowell — Poll showing Platner holds slight lead over Collins in general election matchup (June 4, 2026)
- Real Clear Polling — Aggregate poll data showing Platner at 48.7% and Collins at 41.3%, +7.4 advantage
- The Guardian — Reporting on Platner’s primary and his path to face Collins
- Cook Political Report — Reporting that Janet Mills suspended her campaign facing near-certain primary loss to Platner
- NBC News — Reporting on Mills’ campaign suspension and Platner’s presumptive status as Democratic nominee
- The Washington Post — Reporting on Platner facing controversies and the primary dynamics
- The Maine Monitor — Reporting on Mills’ campaign suspension deadline and why votes for her would still count
