By Lynne Adkins

TRENTON, N.J. (CBS) – Just days before New Jersey’s special U.S. Senate election, the race continues to tighten.

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Democrat Cory Booker remains in the lead over Republican Steve Lonegan, but Patrick Murray, director of the Monmouth University Polling Institute, says that lead is shrinking, according to a new poll.

It was 16-percent just a few months ago, “and now Booker has a 52 to 42-percent lead over Steve Lonegan,” Murray says. “It looks like the big issue is that while voters feel that Corey Booker agrees with them on most of the important issues, they’re still not sure about his motivation about serving in the U.S. Senate.

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Murray adds that Booker’s favorability rating has also slipped over the past few months:

“His positives have come down by ten-points, his negatives have gone up by 15-points, so as people got to know Corey Booker, they didn’t feel as positive as they did when he was just that personality on the TV screen.”

He says Booker is still liked, just not as much as he was before.

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