PROVIDENCE -- A new poll shows Democrat Sheldon Whitehouse in a statistical dead heat with the Republican whose seat he is seeking in the U.S. Senate, and more than 30 points ahead of Sen. Lincoln D. Chafee's GOP primary challenger, Stephen P. Laffey.

Conducted by the veteran Rhode Island polling firm Fleming & Associates for Channel 12 (WPRI), the poll conducted between Aug. 16 and Aug. 21 showed Chafee over Whitehouse, 43-to-42 percent, with 15 percent undecided in a hypothetical matchup.

"The race is within the [4-to-5 percent] margin of error at this point," said pollster Joseph Fleming.

Were Laffey to win the Sept. 12 primary, the Fleming poll of 401 registered voters is the latest in a series to suggest Whitehouse would blow him away: 58 percent to 26 percent, with 16 percent undecided.

Fleming said he did not try to poll where voters stand in the Chafee-Laffey primary contest because finding a credible sample "is very difficult to get because of the limited number of people who vote in a Republican primary."

Fleming surmised that Whitehouse has benefited from months of attack ads coming from the two Republican combatants and their backers.

"I think the Republicans are really hurting themselves in this race in the sense that they are helping the Democrat," Fleming said. "If you think about it, all summer Sheldon Whitehouse has been able to run positive ads, not attack Chafee or Laffey, build a positive image" while Chafee and Laffey do all "the negative."

But while Whitehouse has a formidable lead over Laffey right now, Fleming said he would not write off the Cranston mayor's chances if he knocks off an incumbent in the primary.

Fleming said Laffey first ran for mayor as "an underdog" and won and would undoubtedly get "a bounce" in his poll standings if he defeats Chafee. If he wins the primary, Fleming said, "I also think the Republican Party in the state and nationally would come behind Laffey, which would help his numbers some."

In the possible Chafee-Whitehouse contest, the poll showed slightly more undecided females than males, but women and under-40 voters leaning more to Whitehouse, and over-60 voters to Chafee.

Voters of all ages, male and female, favored Whitehouse over Laffey.

kgregg@projo.com / (401) 277-7078