The second independent poll in a week says that although freshman Democratic U.S. Rep. John Adler is ahead of Republican challenger Jon Runyan, the hard-fought Third District race has the potential to be close all the way to the end.

Adler leads with 40 percent of the vote, with Runyan at 31 percent, according to the Rutgers/Eagleton Poll released Wednesday.

However, polling director David Redlawsk notes that Adler's lead is tenuous because his Democratic base is less enthusiastic than Runyan's Republican base.

"It's always a truism of elections that turnout matters, but in this particular case, it really matters," he said.

Though 58 percent of the Republicans polled said they were "very enthusiastic" about the Nov. 2 election, only 42 percent of Democrats polled felt that way.

"The economic environment is playing in a partisan way. It's depressing Democrats, and I mean depressing them," Redlawsk said. Republicans, he said, "smell blood in the water and are more enthusiastic."

Redlawsk added a note of caution, though.

"This is a snapshot right now," he said. "It doesn't tell us what it will be like in five weeks."

There was troubling news for Runyan in this poll as well. Likely voters in the sample preferred an experienced candidate to an outsider 47 percent to 34 percent. Runyan, a former Eagles tackle, is staging his first political campaign.

The poll of 538 registered voters and 335 likely voters in the Third District, which spans Burlington and Ocean Counties and includes Cherry Hill in Camden County, was conducted between Sept. 23 and 26. It had a margin of error of plus or minus 4.2 percentage points.

Third-party candidate Peter DeStefano came in with 6 percent of the vote.

Redlawsk said he planned to take another poll in late October.

On Monday, Richard Stockton College released a poll showing Adler with 38 percent to Runyan's 30 percent. But the poll sponsor, Sharon Schulman, head of Stockton's William J. Hughes Center, said that because of the poll's five-point margin of error, the race remained close.

Contact staff writer Cynthia Burton at 856-779-3858 or cburton@phillynews.com.