PORTLAND — Democratic Rep Heather Sanborn won her party’s nomination for the Maine Senate District 28 seat Tuesday by defeating City Councilor Jill Duson. The vote was 3,078 to 2,181.

The seat, in a district covering the north and west of Portland and a portion of Westbrook, was opened as incumbent Sen. Mark Dion, sought the Democratic nomination for governor.

Patrick G. Martin, of Westbrook, was unopposed in the Republican primary for the seat.