AP
According to the poll, Booker leads Republican challenger Steve Lonegan, a former gubernatorial candidate and mayor, by a 54-38 margin among likely voters.
Booker's support comes from a coalescing of Democratic voters around him, as Booker earns 92% of the Democratic vote. He only leads Lonegan by 2 points among self-identified Independent voters, a drop from the last Monmouth poll that showed him with a 13-point lead among the group. And Lonegan wins 79% of the Republican vote.
But for Lonegan, there's not much room for movement right now. Only about 22% of voters say they're undecided or could change their vote.
"There is still an outside chance that the dynamics of this race could turn in Lonegan’s favor. But it would take a sea change in partisan turnout to do it," said Patrick Murray, the director of the Monmouth University Polling Institute.
The special election is set for Oct. 16.