If self-styled “values voters” have felt snubbed by the Republican presidential candidates this election season, that snubbing is now official.

Mayor Giuliani, Fred Thompson, Mitt Romney, and Senator McCain are all declining to participate in a September 17 debate in Fort Lauderdale, Fla., that’s being hosted by an umbrella social-conservative group called ValuesVoter.org. Social conservatives will be upset; other conservatives might well be heartened by the waning power of the religious right.

A number of second-tier Republican candidates have confirmed attendance at the event, according to the news site WorldNetDaily.com, whose editor, Joseph Farah, is slated to moderate the debate. They include Rep. Duncan Hunter, Mike Huckabee, Rep. Tom Tancredo, Senator Brownback, Rep. Ron Paul, and John Cox.

The debate will be held at the Broward Center for the Performing Arts and broadcast live on a “Christ-centered” satellite TV service, Sky Angel, as well as streamed over the Web at ValuesVoterDebate.com.

The festivities, however, look likely to go off without a marquee name. Queried yesterday by The New York Sun, the McCain campaign cited a scheduling conflict. “We are not attending,” a spokeswoman for Mr. McCain, Brooke Buchanan, replied by e-mail. “It’s the last day of the No Surrender tour — we will be in South Carolina.”

Likewise, the Romney campaign’s Florida spokeswoman, Gail Gitcho, told the Sun that the former Massachusetts governor had “declined due to a scheduling conflict.”

Mr. Thompson’s press office also is citing “another event on his calendar that day.”

The Giuliani camp didn’t even bother with the scheduling-conflict ruse, providing the Sun with the text of a letter the former mayor’s campaign manager, Michael DuHaime, sent to the debate’s organizers on Friday. “Thank you for your kind invitation for Mayor Giuliani to attend a presidential debate hosted by Values Voters,” Mr. DuHaime wrote. “Unfortunately Mayor Giuliani will be unable to accept your invitation.”

“If they don’t come, it’s their loss,” the founder and president of Eagle Forum and a longtime anti-feminist icon, Phyllis Schlafly, told the Sun.

Ms. Schlafly, who is one of a number of people scheduled to ask questions at the debate, accused the top-tier Republican candidates of “ducking” values voters in the current primary process. “What it shows is that the grass roots are not happy with the ones who’ve been designated as the top candidates,” she said. “Grassroots Republicans are voting for none of the above.”

Most of the top-tier Republican candidates have made at least some effort at outreach to Christian conservatives. Mr. McCain famously spoke last May at Jerry Falwell’s Liberty University, having previously labeled Falwell an “agent of intolerance” back during the 2000 Republican primary. The socially moderate (some would say liberal) Mr. Giuliani spoke this April to televangelist Pat Robertson’s Regent University. Mr. Romney, meanwhile, has been furiously flip-flopping away from the socially liberal positions he took as Massachusetts governor on abortion and gay rights in order to court Christian conservatives. The Thompson campaign, of course, is just getting started, but it has hired numerous consultants to handle religious outreach.

Still, none of this has quashed a feeling among many on the right that the current crop of candidates is not nearly as conservative as the Republican base would like. Mr. Thompson has tried to pitch himself as a “conservative savior” candidate, but he’s unlikely to gain any points with the groups represented by ValuesVoter.org by skipping the organization’s debate.

Without any of the top-tier candidates in attendance, the ValuesVoter.org debate is unlikely to garner much attention from the mainstream press. The question is whether skipping the debate will hurt the Big Four more with the base than attending it might have hurt them with the rest of the country. Given the agenda of those who will be asking the questions — anti-abortion, anti-stem-cell-research, anti-judicial-independence, anti-immigration, and pro-censorship — it’s likely the Fantastic Four made the right decision.