New Jersey Republicans faced a stinging defeat in off-year elections on Tuesday, as three Republican members of the State Assembly were beaten for re-election in a rebuke to the party and Gov. Chris Christie.

Republicans had hoped to build on Mr. Christie’s political successes and cut into the Democratic majority in the chamber, where Democrats currently hold 48 of the 80 seats. Instead, the election became a sharp reality check for allies of the governor, who only two years ago won re-election by a towering margin.

In the First District, on the southern end of the state, a well-funded Democratic campaign ousted Assemblyman Samuel L. Fiocchi, a Republican. In the 11th District, in central New Jersey, two Republican assemblywomen, Mary Pat Angelini and Caroline Casagrande, lost their seats by the narrowest of margins to their Democratic challengers, Eric Houghtaling and Joann Downey.

And in the more conservative 16th District, two Republican lawmakers clung to small leads of a few hundred votes or less, with ballots still being counted.