Philip D. Murphy, a New Jersey Democrat whose aggressive approach to controlling the pandemic became a focal point of the bid to unseat him, narrowly held onto the governor’s office in an unexpectedly close election that highlighted stark divisions over mask and vaccine mandates, even in a liberal-leaning state.

With roughly 90 percent of the vote tallied, Mr. Murphy was ahead of his Republican challenger, Jack Ciattarelli, by less than 1 percentage point when The Associated Press called the race just before 6:30 p.m. on Wednesday after a protracted count. The bulk of the outstanding votes were in Democratic strongholds.