Commentary by Margaret Carlson

(Bloomberg) — Fred Thompson has had one of the more inauspicious beginnings to a presidential campaign, all downhill since the swoon he induced among many Republicans when he said in March he was testing the waters.

As spring turned into summer and weeks into months, the swoon turned into foot-tapping impatience. The good news about an inauspicious beginning is that it's just a beginning.

Thompson's New, New Campaign began Wednesday night when the former senator from Tennessee announced he was running for president, from the comfort of a couch on the "Tonight Show."

Those who are already running didn't much like that. While Thompson (R-Hollywood) was joshing with Jay Leno before an audience of millions about how much harder it is to get on Leno than into a debate on Fox television, his opponents looked like schoolchildren lined up to be grilled by Brit Hume, who thinks he's smarter than all of them.

Hume, who wanted to show you don't mess with Fox, gave each candidate a chance to take a shot at Thompson, which proved Thompson right to mess with Fox. The Man Who Wasn't There became the focus of the first five minutes of the debate. He later interjected himself by tape into the program with a paid spot.

It all served to give Thompson, who's 64, the lion's share of coverage coming out of the debate he stiffed. The next day, Thompson proceeded to a more orthodox rollout across four states on a bus tour following a formal announcement in Des Moines, Iowa. His crowd there was respectable for daytime, but not ardent. The event opened with a video biopic, so Thompson in the flesh was something of a letdown.

That disconnect highlights the danger of moving from movie star to candidate, from the white knight of a party that sees him as conservative enough to nail down the base and reasonable enough to win the general election.

Thompson still has to show he can pull a campaign team together. On the eve of his Leno appearance, he lost top aide Jim Mills, wooed away just weeks ago from a good producing job at Fox TV by Thompson and his wife at their dining room table. The day after Leno, he lost Mark Corallo, a highly regarded operative who had been helping out since April.

These dismissals are an effort by the latest campaign manager, Bill Lacy, to purge anyone who arrived before he did and who might have a back-channel to the candidate.

That might mean dismissing Thompson's wife, Jeri. Although she's done little more than any other spouse, including Hillary Clinton when Bill was a candidate or Rudy Giuliani's wife now, she's become a household name as the prototypical meddling wife in over her head, responsible for every misstep. (She's also become a household face; she's 24 years younger than her husband and photogenic.)

Thompson also has to hone a message beyond "security, unity, prosperity." If he's to pick up the mantle of Ronald Reagan he can't touch down at the Iowa State Fair for all of two hours in Gucci shoes and a golf cart.

By not getting in sooner, Thompson fed talk that behind the easygoing charmer is an easygoing charmer who's winged it for years. I've known Thompson since he came to the Senate, and Newsweek's cover line this week — "Lazy Like a Fox" — captures the determination behind the laid-back exterior.

He may seem like George W. Bush, gliding through life and grabbing all its breaks, but Thompson went from being a husband, father and college dropout, to winning a scholarship to Vanderbilt Law School, where he graduated near the top of his class at age 25.

From then on, it looked easy as he became the kind of young man that old men choose to sit at the table. He was selected to serve as counsel to the committee investigating Watergate and to run for a Senate seat as a political novice.

He lucked into acting. When a movie was being made of his crusade to send a governor to prison for selling pardons, he was asked to play himself. He's been doing it in dozens of movies ever since and on the TV program "Law & Order" for the last five years.

As for being a slacker, who wouldn't find the Senate's 14- hour days frustrating and much of its work irrelevant? But when Thompson lost a daughter to an accidental prescription-drug overdose in 2002, he had no patience for it and left.

He remarried, had two children and suffered through non- Hodgkin's lymphoma, now in remission, all of which lends perspective to ambition.

A modern presidential campaign is grueling, with way too many hours begging for money. No wonder he waited until the last moment.

He's going to pay for that in the short run from his opponents, who resent his parachuting in. John McCain was Thompson's best friend in the Senate but tweaked Thompson's reputation for not overworking himself, saying he skipped the debate because "we're up past his bedtime."

Giuliani took a swipe at Thompson's preference for acting tough to being tough. "He's done a pretty good job of playing my part on `Law & Order,"' the former prosecutor and mayor said. "I personally prefer the real thing."

Thompson's opponents will try to make him out to be the quitter who preferred the soft life of a lobbyist and movie star to serving his country. He will play the non-career politician somewhere in between the graphite perfection of Mitt Romney and the aw-shucks persona of Mike Huckabee, the man who wants to be president but doesn't hunger for it. That's what the public says it wants. Thompson will soon find out.

(Margaret Carlson, author of "Anyone Can Grow Up: How George Bush and I Made It to the White House" and former White House correspondent for Time magazine, is a Bloomberg News columnist. The opinions expressed are her own.