The new survey cements the trend seen in a number of polls released over the past three weeks that have shown Booker's lead tightening somewhat, and considerably smaller than it was mid-summer, when he often posted a lead in the mid-20s or high teens.
Booker previously led by 13 points in another Monmouth University poll out two weeks ago.
But his campaign insists it's not concerned, and chalks the tightening polls up to voters tuning in as the Oct. 16 Election Day nears.
Booker has also faced a steady stream of negative press since he entered the race. In recent weeks, media reports have raised questions about his role in a startup he founded that faltered before he divested himself of his investment in it; stories he tells on the campaign trail about a character from the rough part of Newark that appears not to exist; and details about his flirtatious interactions with a stripper on Twitter.
And Lonegan has received some attention from national GOP groups and figures as the race appears to tighten, with the National Rifle Association endorsing him and Sarah Palin stopping in the state to stump for the former mayor on Saturday.
Still, a double-digit lead just three days out from the election will be hard for Lonegan to beat, and New Jersey remains a deeply blue state, which Obama won with nearly 60 percent of the vote last cycle.
The survey was conducted among 1,393 voters from Oct. 10-12 and has a margin of error of 2.6 percentage points.