It’s not as eye-opening as the recent polls showing GOP challengers leading Democratic incumbents in the House, but Jon Runyan has to feel pretty good about this early poll:

U.S. Rep. John Adler (D-Cherry Hill) holds a slender lead over Republican challenger Jon Runyan, among all registered voters according to a Rutgers-Eagleton Poll released this morning.
Adler leads Runyan 31% to 25%, with third party candidate Peter DeStefano polling at 4%. Thirty-four percent of respondents say they “don’t know” who they support, while another 6% say they will not vote in the Congressional race.
In a mano-a-mano, Adler leads Runyan 35% to 28%, according to the poll, with 23% in the “don’t know” category and 13% not voting… The poll has a margin of error of +/-4.8 percentage points.
“It is extremely hard in August to predict who will really vote in November,” said poll director Dr. David Redlawsk. Thus, while a simple likely voter screen suggests that Adler does better, we do not put a lot of stock in such a screen at this point. It remains too early to be sure who will be most motivated to turn out on election day.”
The poll reports that Adler leads among all registered voters, but Runyan pulls just ahead (36 to 35%) among voters “who are paying the most attention to the campaign.”

These strike me as pretty weak numbers for an incumbent, even a first-termer.