PROVIDENCE -- Rhode Island's closely watched U.S. Senate race is now a dead heat between Lincoln D. Chafee, the Republican incumbent, and his Democratic challenger, Sheldon Whitehouse, according a new Brown University poll.

The results of an automated poll released earlier this week by national pollster Rasmussen Reports had Chafee trailing Whitehouse by 8 percentage points as he emerged from last week's fiercely contested GOP primary.

The Brown poll released yesterday suggests a much closer race.

If the election were held today, 40 percent of the 578 likely voters surveyed said they would vote for Whitehouse and 39 percent for Chafee, with 21 percent undecided. (The error margin is 4 percentage points).

Other highlights of the poll conducted between Saturday and Monday by Brown Prof. Darrell M. West, the director of the university's Taubman Center for Public Policy:

Republican Governor Carcieri's lead over his Democratic challenger, Lt. Gov. Charles J. Forgarty, has widened to 12 percentage points. Carcieri now leads Fogarty 50 percent to 38 percent. (In June, Carcieri led 44 percent to 39 percent.)

A growing majority of Rhode Islanders oppose the ballot drive to change the state Constitution to allow the proposed West Warwick casino, despite the $5.2 million the Las Vegas-based Harrah's Entertainment has spent since June to try to influence public opinion.

Opponents of the proposed Harrah's-Narragansett Indian casino outnumber supporters 55 percent to 36 percent and the gap has widened. In June, the split was 52 percent to 39 percent against the Nov. 7 ballot proposal.

Narragansetts Chief Sachem Matthew Thomas said the poll "doesn't reflect what I'm hearing from Rhode Islanders. . . . What I'm hearing from Rhode Islanders is that they want property tax relief, they want job creation . . . and they know that the Narragansett Indian casino will provide that, as well as generating additional state revenues for critical services such as health care, education, and much-needed transportation improvements.

But the Brown poll detected deep skepticism about a central promise of the casino campaign: property tax relief.

Only 39 percent said they believed the casino would help reduce taxes; 46 percent did not; 15 percent were undecided.

The Chafee camp was heartened by the new poll, which came out one day after the Rasmussen poll showed Whitehouse ahead 51 percent to 43 percent.

"We feel really good about where we are coming out of a tough primary," Chafee campaign manager Ian Lang said yesterday. "We feel like we've got great momentum."

But Whitehouse spokeswoman Alex Swartsel said any poll showing an incumbent senator with less than 40 percent of the vote shows weakness.

"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 [objective] 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."

Focusing on President Bush's abysmal 22-percent approval rating in Rhode Island, she said: "Over three-quarters of people . . . in this state believe the president is doing a bad job."

"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."

But Lang tried to keep the focus on Chafee versus Whitehouse.

He said the poll shows Chafee right up there with Whitehouse, who had only token opposition in his own party primary 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 suggested, they "really appreciate" Chafee's independence and "willingness to take the tough votes."

West said he, too, thought Chafee would have suffered more of a backlash than he did from a bitter and divisive primary race against Cranston Mayor Stephen P. Laffey, but 83 percent of those identifying themselves as Republican fell in line behind him, as did 17 percent of Democrats and 33 percent of the union vote. Chafee led Whitehouse 43 percent to 34 percent among independents.

Chafee also emerged with a 51-percent job-approval rating that did not measure up to Democratic Senate colleague Jack Reed's (70 percent), but topped U.S. Rep. Patrick Kennedy's (43 percent).

West anticipated a close race right up until the end between two strong candidates, but he called those "pretty good numbers for someone subjected to months and months of intense criticism."

Clearly, the Democrats "want to nationalize this campaign and run against George Bush, while the Republicans want to personalize the race and emphasize Chafee's positive qualities." For now, "it's a dead heat."

West has theories about why his own live-interview poll last weekend produced different results in the U.S. Senate race from Rasmussen's automated poll a day after the Sept. 12 primaries.

He said the Rasmussen survey has "consistently had a pro-Democratic bias," which he attributes to a "slightly" tilted sample and a "dubious" methodology that forces people who may be undecided to think they need to make a choice.

Pollster Scott Rasmussen acknowledged last night that people were asked if they would support Republican Chafee or Democrat Whitehouse and if they favored Chafee to press a number, Whitehouse, another number -- and only then given a chance to indicate that they were uncertain or favored another candidate.

But Rasmussen said there is evidence people feel freer in automated polls to say they support a challenger or lesser known candidate than they do when talking to a live person. He said timing makes a difference.

Rasmussen also also suggested that both polls contain a caution for Chafee: "Any incumbent, at this point, who is below 50 percent is considered by most analysts to be in some level of trouble."

In the governor's race, West believes Carcieri's TV advertising campaign has helped him and that "Fogarty's attacks have not yet caught on." Example? "He has an ad talking about corruption, but I don't think anyone thinks the governor is corrupt."

Carcieri campaign manager Ken McKay said the numbers are "more in line with where our numbers have been" than some other polls showing the two nearly tied.

Fogarty spokesman Adam Bozzi said: "I think most of the polls overall show it's a competitive race, and that's what we are comfortable with."

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