A telling moment in this week's Republican debate in Michigan came near the end, when each of the presidential candidates was asked to talk about labor unions.
Fred Thompson, making his first appearance in one of these multicandidate contests, smiled his self-confident smile and observed that he was actually a member of a union.
"The Screen Actors Guild still counts, doesn't it?" Thompson asked, with a knowing chuckle.
The former senator and current TV actor clearly expected his audience, or at least some of it, to register the full meaning of this reference to SAG. It's the same organization that Ronald Reagan headed up in the 1940s and '50s. In that role, the Gipper testified to Congress about communists in the movie industry and began his long journey from Hollywood to Washington, from the left to the right and from actor to president.
Thompson, of course, is chiefly interested in the part about going from actor to president. And while his career has also included substantial time as a Hill staffer, trial lawyer, lobbyist and U.S. senator, Thompson likes to mention the acting as often as he can.
In this week's debate, rival Mitt Romney had a gag about Thompson showing up toward the end of the primary season, much as he shows up toward the end of episodes of TV's Law and Order.
Thompson came back with: "And to think I thought I'd be the best actor on stage."
It's hard to remember now that, 40 years ago, Reagan had to live down his show business reputation to be viable in national politics. Today, Thompson knows his actor identity is the main source of the name-and-face recognition that makes him viable in national politics. Even more important, his actor credential is the biggest reason people compare him to Reagan.
Being mentioned in the same breath as Reagan remains the single best credential a Republican can have, no matter what he's running for. You got all the proof of that you needed in the first GOP debate of the 2008 election cycle, held in California at the Reagan library and dedicated to Reagan's legacy.
Thompson, joining the field several months after that debate, is still catching up on the Reagan hagiography scoreboard. But he manages to mention the man and invite the connection frequently on the stump.
Of course, Thompson is not the sort of actor Reagan was, in either the thespian sense or the political. At his peak, Reagan was a studio matinee idol, a leading man who, in his own phrase, "always got the girl." His face was in magazine ads, his family life was featured in LIFE magazine.
His star declined in the 1950s, but in his heyday, he had some of the myth-making power of his more durable contemporaries such as Stewart, Bogart and Tracy. He personified America's notion of itself as both good-hearted and tough-minded, wised-up and amiable at the same time. He made his contribution to the national consciousness.
Thompson has never approached this plane of pop-culture importance. True, he taps into certain archetypes in his movies, playing an admiral, a lawyer, a businessman and a White House chief of staff. But these parts have generally been little more than cameos. His continuing TV role, Manhattan district attorney Arthur Branch, is little more than a stock character.
So Thompson scarcely evokes the kind of nostalgia Reagan always did, that potent memory of an America now gone but fondly remembered. He tries at times, but the effect is muted at best.
If the two men do not carry the same weight in show-business terms, the comparison is even more strained when it comes to politics. Reagan in the 1960s became the Election Day champion of a broad and complex movement that had been building since the 1930s, a challenge to the politics of the New Deal and all that came after.
In bruising campaigns, Reagan defeated an incumbent Democratic governor in California in 1966 and an incumbent Democratic president in 1980. In between, he nearly defeated an incumbent Republican president for the GOP nomination in 1976. Finally, he won re-election to the White House in 1984 by carrying 49 states.
Thompson, by contrast, won an open Senate seat in the best Republican election year in half a century and was re-elected against a sacrificial lamb. Uninspired and uninspiring in the Senate, he retired in 2002. Now, as he enters the 2008 presidential contest months late and offers little that sounds new or different, Thompson could scarcely be less Reaganesque.
By inviting the comparison, he clearly hopes to cast himself as a latter-day heir, with all the attending aura of drama and history. But if he fails the test the comparison implies, he will not only fail to be Reagan, he will fail to be the candidate he might have been in his own right.