Council President Matt Moench defeated incumbent Mayor Dan Hayes by 1,083 votes in the Republican primary Tuesday.
Moench will face Democrat Jeffrey Brookner in the general election.
Moench’s 26-point win was enough to carry his council candidates, Michael Kirsh and Timothy King across the finish line, unseating incumbent Councilwoman Christine Rose Henderson.
Bridgewater Republicans voted in February to endorse Moench, but the Somerset County Republican organization decided to give their line to Hayes.
Moench has been a councilman since 2008 and served as deputy chief of staff to Gov. Chris Christie in 2016. He is a former assistant commissioner of Banking and Insurance.