Polls are open from 6 a.m. to 8 p.m. for the special election to fill the unexpired term of longtime Sen. Frank Lautenberg.
Newark Mayor Cory Booker started off the general election campaign in August with a lead of more than 30 points in some polls against Republican Steve Lonegan, a former mayor of Bogota.
But in recent weeks polls have shown the margin close to 11 points, and Lonegan campaign staff has said internal polls show a gap of as little as six percent.
While Booker still remains a favorite at the polls, some analysts have said that turnout, which was slim for the primaries, could make things unpredictable, given the odd timing of a Wednesday election coming less than a month before New Jersey goes to the polls to vote for governor.
Glen Rock's Borough Council meeting, originally scheduled for 8 p.m., has been cancelled due to the special election.