AUGUSTA — A new poll shows oyster farmer and military veteran Graham Platner leading Gov. Janet Mills by seven percentage points in the Democratic primary for the U.S. Senate.

The Pan Atlantic Research Omnibus Poll puts Platner at 46% support among likely Democratic primary voters compared to Mills at 39%. The poll lists 11% undecided and David Costello, who mounted an unsuccessful bid for the U.S. Senate two years ago, at 4%.

The results are based on a sample of 810 likely voters with a margin of error of 3.7%.

When it comes to a potential matchup with incumbent Republican Sen. Susan Collins, the poll found Platner ahead with 44% support to 40% for Collins. That leaves 16% undecided. 

In a matchup with Mills, the poll showed a tie with both Mills and Collins at 44%. Undecided came in at 12%.

The latest batch of polling data ahead of the June party primaries follow results released last week that showed Platner ahead of Mills, with 64% support, compared to 26% for Mills. That survey was conducted by the University of New Hampshire Survey Center.

Platner and Mills are locked in a battle for their party’s nomination in the June 9 primary. The winner will face Collins, who is seeking her sixth term to the Senate.

The November race has national implications, with Democrats needing to flip four seats — including the one in Maine — to take control of the Senate. 

A December Pan Atlantic poll showed Mills leading Platner by 10 percentage points, 47% to 37%, with 13% undecided.