With barnyard sound effects and toe-tapping music reminiscent of The Beverly Hillbillies, the conservative Club for Growth is attacking U.S. Sen. Lincoln D. Chafee in a new television advertisement that paints the Republican incumbent as "just another tax-and-spend politician."

The Club for Growth, an influential anti-tax organization that can steer millions of dollars into political races nationwide, supports Stephen P. Laffey, the two-term Cranston mayor who is challenging Chafee in the Sept. 12 GOP primary.

The Club is a Republican advocacy group, and it's taking a calculated risk in backing a challenger against a sitting Republican U.S. senator in one of the most Democratic states in the nation. "There are risks to this race," the Club says in an endorsement of Laffey on its Web site. "Probably, there are more risks than any other recommendation we will make for 2006."

One risk is that a battered Chafee could survive the primary but lose the seat to a Democrat in November.

Club for Growth President Pat Toomey, a Rhode Island native and a former Pennsylvania congressman, said in an interview last night that the risk is worth taking.

"We have always thought that whoever wins the Republican primary is going to have a tough but winnable race in November," Toomey said. "We wouldn't have gotten into this race if we didn't think Steve Laffey could win."

The Republican who prevails next month will probably face Democrat Sheldon Whitehouse in the general election. The former U.S. Attorney and state attorney general is expected to defeat businessman Carl Sheeler, a political newcomer, in the Democratic primary. Without a well-financed primary opponent pounding him over the air, Whitehouse has enjoyed a summer of building his image through issue ads that play off dissatisfaction with Washington and the Bush administration. [President Bush is more unpopular here than in any other state; a SurveyUSA poll released Tuesday puts the president's job approval at 22 percent in Rhode Island.]

Meanwhile, Laffey and Chafee have been roughed up in a bare-knuckled primary that has grown increasingly edgy.

This Rhode Island race is only the second time the Club for Growth has sided against a sitting Republican senator in a primary, Toomey said. The first time was two years ago, when Toomey challenged U.S. Sen. Arlen Specter, R-Penn., in a race Specter won by less than two percentage points.

Toomey sees some obvious similarities between his race against Specter, and Laffey's run against Chafee. Toomey's campaign, heavily backed at the time by the Club for Growth, attacked Specter as too liberal on federal spending. Laffey has blistered Chafee for tolerating "government pork," relentlessly citing "taxpayer rip-offs" in spending bills that Chafee has supported.

"The big difference between the races," Toomey said, "is that in my race I got outspent four-to-one." With just one media market in Rhode Island, a statewide race here is relatively economical -- certainly when compared with Pennsylvania. "Steve Laffey is going to have the good fortune to be able to bring his message to the voters."

Toomey played down the prospect of Laffey's challenge weakening Chafee and delivering the seat to Sheldon Whitehouse. "That's for Linc Chafee and the Republican Senatorial Committee [which supports Chafee] to worry about."

But in its endorsement of Laffey on its Web site, the Club acknowledges: "One risk is that, after beating Chafee in the primary, Laffey loses the general election to the Democrat. But the odds of this happening are not overwhelming -- and we believe this risk is acceptable."

The Club argues that Chafee is the most liberal Republican in the Senate, and the chance to replace him is worth this risk for several reasons:

"First, it wouldn't be much of a loss if a new Democrat senator were elected, as he would vote much the same as Chafee does now," the Club claims. "Second, it is unlikely this loss would result in tipping control of the Senate back to the Democrats -- though that, too, can't be ruled out. If Republicans lose so many seats that the Rhode Island race is crucial, Chafee would probably lose, too."

The national pollster Rasmussen Reports says Whitehouse has built a narrow lead over Chafee in a theoretical match-up, and that the Democrat maintains a double-digit lead over Laffey.

Chafee's campaign has recently pushed the theme of "electability," claiming that Chafee is the only Republican in the state who can beat Whitehouse.

"That's a pretty sorry argument for an incumbent," Toomey said. "That's it? Vote for me, I'll have an "R" after my name?"

The Club for Growth's new attack ad recycles themes used against Specter in 2004. The ad, which went up on Tuesday, welcomes viewers to "Lincoln Chafee's Wide World of Wasteful Spending" and blasts Chafee for supporting pork projects, including the infamous $200-million "bridge to nowhere" in Alaska, which has come to epitomize federal pork gone wrong. The ad also claims Chafee supported federal money for "an indoor rainforest in Iowa" and "the Montana sheep institute." It also accuses him of supporting "over a trillion dollars in higher taxes."

"Lincoln Chafee's spending," a weary announcer claims at the end, "is just too taxing."

The Chafee campaign defends each of the senator's votes. The "bridge to nowhere," which Laffey has already made into a campaign issue, was part of a massive transportation bill that also delivered money for a new train station, among other projects, to Rhode Island. Chafee claims that a vote against the bridge would have jeopardized the whole transportation bill.

The other projects cited by the Club were also part of massive spending bills to pay for nearly every aspect of the federal government, says Ian Lang, Chafee's spokesman. "These bills are for the funding of government, and they are up or down votes," he said. He notes that each bill passed "with overwhelming Republican support."

"These items are why Senator Chafee is a strong supporter of giving the president the line-item veto," Lang said.

The charge that Chafee supported higher taxes apparently comes from his opposition to tax cuts pushed by President Bush. The senator has cited huge federal deficits in defending his opposition to the tax cuts.

"What the Club for Growth has done since day one is take things out of context," Lang said. "Most Rhode Islanders understand that Senator Chafee is tight with their tax dollars." He objected to the Club's "party-purity" test for Republicans, which he says allows no room for political moderates. "They are pursuing their narrow agenda, and they do not have the interests of Rhode Island or the Rhode Island Republican Party at heart," he said.

Chafee and Laffey will debate at 5 this afternoon on WPRO radio's Dan Yorke Show.

marsenau@projo.com / (401) 277-7231