With ballots counted from all but one of Northampton County's 157 polling precincts, unofficial results show Zrinski ahead by roughly 13.7% of the vote.
Unofficial results show incumbent Mayor Matt Tuerk handily defeating Councilman Ed Zucal. The mayor has earned just over 80% of the 5,100-plus votes counted by 10:30 p.m.
Incumbent Easton City Council members Taiba Sultana and Roger Ruggles lost in the Democratic primary, according to unofficial election returns. Susan Hartranft-Bittinger defeated Sultana and Frank Graziano outpaced Ruggles.
Polling places across the Lehigh Valley faced mainly light turnout throughout Primary Election Day, with early morning turnout lagging.
So far, two Macungie residents have applied to fill an open seat on the borough council. On Monday, the body's current members asked them a few questions.