WASHINGTON — The 10 Republican presidential candidates will meet in New Hampshire today for their second debate, yet the prospective candidate with the most buzz will not even be on stage.

Former Sen. Fred Thompson, R-Tenn., perhaps best known for an acting career that includes a role on the popular TV series "Law & Order," established a preliminary campaign committee Friday and has all but announced he will enter the race.

This may cause a shake-up among the contenders — with some experts singling out former Massachusetts Gov. Mitt Romney — while others say it is too soon to tell how the actor-turned-politician will affect the race, if at all.

Romney, who led Salt Lake City's successful 2002 Winter Olympics, leads the polls in Iowa, where the presidential primary season will kick off in January, and has earned top-tier GOP candidate status alongside former New York Mayor Rudy Giuliani and Sen. John McCain, R-Ariz.

But some believe that a Thompson candidacy could change that as the man who plays a tough-talking New York district attorney on TV could fill the conservative slot on the Republican ticket that Romney has worked since day one to claim.

"(Romney's) the conservative alternative to Giuliani right now," said David E. Johnson, CEO of Strategic Vision LLC, a Republican public affairs firm. "But they (conservatives) don't have the same reservations about Thompson as they do about Romney."

Johnson said some conservatives are still "leery" that Romney will run as a conservative but then resort to more moderate positions on key issues such as abortion and gay rights that he had when running in 1994 against Sen. Ted Kennedy, D-Mass. With possibly two Supreme Court seats coming up during the next presidential term, some conservatives do not want to take the chance, Johnson said.

The religion factor

Religion is also a factor, "playing a larger role than people will admit," said Mark Caleb Smith, director of the Center for Political Studies at Cedarville University in Ohio. Romney is a member of The Church of Jesus Christ of Latter-day Saints, and Thompson is a member of the Church of Christ.

Right now, Romney looks like the more credible conservative candidate, but conservatives are "still uneasy about his Mormonism, so they will look to Thompson," Smith said.

Smith, who specializes in research on religion and politics, said some religious conservatives, particularly in the South, still see Mormonism as a cult and would have a hard time putting a Mormon in the White House, while Thompson would not have to overcome that hurdle.

"He is a Southern religious conservative; he can speak to conservatives in a way the others cannot," Smith said, adding that Thompson has "consistency" in his statements while "Romney has to start every press conference or statement almost with a disclaimer."