WASHINGTON -- Fred Thompson sat at the end of a long table in The Monocle restaurant on Capitol Hill Tuesday night for dinner with some 20 fellow conservatives, mostly journalists. He sent two signals. First, he sounded like a man who has decided to run for president. Second, his candidacy will be something different from other Republicans, in both substance and style.

This was one of the irregular sessions of the Saturday Evening Club, which is not a club and never meets on Saturday. The name was purloined from H.L. Mencken's Baltimore discussion club by R. Emmett Tyrrell Jr., editor-in-chief of The American Spectator. Tyrrell arranges and presides over these events, always featuring a guest newsmaker -- usually a Republican presidential hopeful over the past two years. Former Sen. Thompson was the most intriguing of them because he has become a leading prospect for president even though he has not announced his candidacy and has no real campaign.

Thompson's performance Tuesday night, with his remarks off the record, helped show why many Republican insiders are ready to support him. Thompson is winning straw polls at Republican conferences and running well in polls mainly because of dissatisfaction, for varying reasons, with the three leading GOP candidates -- Rudy Giuliani, John McCain and Mitt Romney. But Thompson at the dinner table confirmed the widespread perception inside the party of his potential to be an extraordinary candidate.

Thompson disappointed in his first speech as a prospective candidate, addressing the Lincoln Club of Orange County, Calif., on May 4. Discarding a speech he had written himself, Thompson ad-libbed from handwritten notes, a performance that placed him in the usual run of Republican after-dinner speakers. This was not the second coming of Reagan that Californians envisioned. Was all the excitement about Thompson merely engendered by his television role as the formidable Manhattan district attorney on "Law and Order"?

He stuck to his prepared cards for his second speech, at a Republican state party function in Stamford, Conn., last week, and it was a considerable improvement. It sounded more like an off-the-record conversation he had with me in Orange County, Calif., before his speech there, and his Saturday Evening Club conversation.

The Connecticut Republicans, down to one seat in Congress after 2006 election losses, cheered when Thompson told them: "I think the biggest problem we have today is what I believe is the disconnect between Washington, D.C., and the people of the United States. People are looking around at the pork barrel spending and the petty politics, the backbiting. The fighting over all things, large or small, is creating a cynicism among our people." That cynicism, Thompson contends, mandates a different kind of campaign for 2008.

Thompson implied at Stamford that Republicans, along with Democrats, are responsible for making Americans cynical. While so far not spelling this out publicly, he deplores ethical abuses, profligate spending and incompetent management of the Iraq war. He becomes incandescent when considering abysmal CIA and Justice Department performance under the Bush administration. He is enraged by Justice's actions in decisions leading to Scooter Libby's prison sentence.

In his Senate voting record and his public utterances, Thompson is more conservative than Giuliani, McCain or Romney. He takes a hard line on the war against terror (referring in Connecticut to the danger of "suicidal maniacs" crossing open borders) and worries about immigration policy creating a permanent American underclass. His one deviation from the conservative line has been support for the McCain-Feingold campaign reform, much of which he now considers overtaken by current fundraising practices and perhaps irrelevant. Overall, his tone, in a soft Tennessee drawl, is less harsh than that of other Republican candidates -- a real-life version of the avuncular fictional D.A. he plays on TV.

Beyond ideology, Thompson envisions a 21st-century campaign, utilizing the Internet more and spending less money than his opponents. When speaking to a friendly audience or ruminating off the record, the 6-foot-7 actor-politician does not look or sound like the GOP's announced candidates for president. His challenge will be to convey that impression when he appears with opponents on the same stage in the immediate future.