PROVIDENCE -- Incumbent Republican U.S. Sen. Lincoln D. Chafee and his Democratic opponent, Sheldon Whitehouse, are locked in a close race, according to a Brown University poll released this morning.

If the November general election were held today, 40 percent of Rhode Islanders polled would vote for Whitehouse, while 39 percent would cast their ballots for Chafee. Twenty-one percent of those polled Sept. 16-18 were still undecided.

The poll was conducted by Darrell M. West, director of the Taubman Center for Public Policy and the John Hazen White Sr. Public Opinion Laboratory. It is based on a statewide random sample of 578 likely voters in Rhode Island. Overall, the poll had a margin of error of about plus or minus 4 percentage points.

The Brown poll is the second released since last week’s GOP primary, which Chafee won after a bitter fight with challenger Cranston Mayor Stephen Laffey. It shows a closer race than the Rasmussen Reports poll that became public yesterday.

That poll showed Chafee trailing Whitehouse by 8 percentage points, with 51 percent supporting Whitehouse and 43 percent supporting Chafee.

The Chafee camp was heartened by the new poll, while Whitehouse spokeswoman Alex Swartsel said any poll showing an incumbent senator with less than 40 percent of the potential vote shows weakness.

“In large part I think that’s attributable,’’ she said, “to the fact that Rhode Islanders have spent the last several months watching this Republican president and this Republican administration and their Republican allies come into this state with the clear object of saving Senator Chafee because they understand that if he’s reelected he’ll go back down to Washington and vote to keep a Republican majority in power which will continue the country on the wrong path."

But Chafee campaign manager Ian Lang said the poll shows Chafee right up there with Whitehouse, who had the luxury of running basically unopposed while “we have been engaged in one of the most contentious primaries in recent history.’’

Now that voters have had a chance “to catch their breath and actually look at the two candidates,’’ he said, they “really appreciate’’ Chafee’s independence and “willingness to take the tough votes,'' he said.

"We feel really good about where we are coming out of a tough primary,’’ he said. “We feel like we’ve got great momentum and we’re looking forward to winning in November.’’

On the casino front

The Brown poll also asked respondents to weigh in on another key vote on the November ballot -- the casino question.

More than half of those polled, or 55 percent, oppose amending the state Constitution to allow a gambling casino in West Warwick operated by Harrah’s in association with the Narragansett Indian Tribe. The Brown poll shows 36 percent favoring a casino and 9 percent undecided.

Narragansett Indian Chief Sachem Matthew Thomas dismissed today's results, saying:

Governor's race

The poll also shows Republican Governor Carcieri well ahead of his Democratic challenger, Lt. Gov. Charles Fogarty. Carcieri now leads Fogarty with 50 percent of likely voters supporting him to 38 percent supporting Fogarty, up from a 44 percent to 39 percent Carcieri lead in a June poll.

How's Bush doing?

Only 22 percent of Rhode Island voters believe President Bush is doing an excellent or good job, with just 4 percent of those saying he’s doing an excellent job.

Twenty-one percent of those polled said the Republican Bush is doing an “only fair” job, 55 percent said he’s doing a poor job and 2 percent either said they didn’t know or did not answer the question.

Whitehouse spokeswoman Swartsel noted, "What Senator Chafee’s challenge is over the next several weeks is having to explain to Rhode Islanders why keeping George Bush’s agenda alive in Congress with continued Republican control in the Senate is going to be good for this country and that’s a very difficult argument to make.’’

-- With reports from Journal staff writer Katherine Gregg