Joseph Signorello, Jr., who became mayor in January after his son resigned to become a Union County Commissioner, holds a razor-thin lead of six votes in the Democratic primary.
In a race against First Ward Councilman Gregory Johnson, Signorello is ahead, 585-579, in a contest that is too close to call.
Signorello is a former councilman, school board member and fire chief. His son, Joseph Signorello III, won the 2018 mayoral race with 54% of the vote in a three-way race that included incumbent Democrat Carl Hokanson, who ran as an independent.
Republicans are running Jorge Ramirez, who ran for the second ward two years ago
Roselle Park has become a Democratic stronghold; Mikie Sherrill carried Roselle Park by 25 points last year.