OPKINTON, N.H. - Senator John McCain was well into his comic riff about being a POW in Vietnam - joking about how it hadn't taken a lot of talent to intercept a missile with his own plane, lamenting that his kids thought Danny DeVito, not Tom Cruise, should play him when his life story is made into a movie - when suddenly the curtain behind McCain tumbled down and blanketed a couple of his staffers.
The big town-hall audience, already nicely warmed up by the GOP presidential candidate despite a 30-below wind chill outside and the fact that it was only 7:45 a.m., howled at the sight gag.
''I think I've identified the problem,'' McCain cracked as the fallen curtain exposed a photographer with a ladder and sheepish grin as the guilty party. ''The worst kind of infiltrator!'' cried McCain, who had gotten a laugh earlier calling the press corps covering him ''communists and Trotskyites.''
Campaigning for president in the weeks before the first primary contest here is serious business. But fortunately, not all the time.
Even Al Gore, that stiff and earnest policy wonk, is trying to show voters he is lightened and loosened up. One of his favorite jokes, which happens to play off his argument with rival Bill Bradley over health insurance, is about the HMO director who shows up at the pearly gates and asks for admission to heaven. ''Sure,'' the vice president says, quoting St. Peter, ''but you can only stay two days.''
''Gore should really let people see that he has this less serious, unscripted side,'' Karen Golec, a special education teacher, said after attending a Salem event where Gore strolled around like a stand-up comic, bantering with the audience and joking about being a grandparent. ''I feel more positive about him, knowing he can laugh at himself,'' Golec said.
Any political strategist will tell you that the right dose of self-deprecating humor is an important campaign ingredient. It can humanize a candidate, setting him or her apart in a crowded field. And it can soften or alter a negative image that either the media - or, worse, Jay Leno - are creating for millions of Americans. Hillary Rodham Clinton, who is running in New York for the US Senate, appeared on David Letterman's show last week after lots of taunting and years of needling, and got rave reviews as witty and a good sport.
Perhaps because the field is so big, the need to be a star is so urgent, and the GOP's 11th Commandment - thou shalt not bash your opponent - is taken somewhat seriously, the Republicans are coming up with a lot more laugh lines than the stern combatants on the Democratic side.
Texas Governor George W. Bush, who jokes that he gets his big mouth from Barbara, his mother, often uses humor to blunt the barbs about his IQ. Bush's comic comeback is that well, OK, maybe I'm not so smart - at least when it comes to baseball sluggers. ''As you may remember I was in the business world at one time, and as managing general partner of the mighty Texas Rangers, I signed off on that wonderful transaction: Sammy Sosa for Harold Baines.''
McCain drew a laugh when the moderator of a New Hampshire debate asked about his reputation for having a bad temper and few friends among fellow Republicans.
''You know, a comment like that really makes me mad,'' McCain deadpanned, paused, and then with a twinkle, went on to say that he is well-liked by everybody but Washington's greedy special-interest groups.
''Humor is a wonderful way for candidates to connect to people, cut through a lot of malarkey, and make a point in a very effective way,'' said Robert Dallek, a presidential historian at Boston University.
The art of the political put-down is particularly useful in this presidential campaign. The candidates are under so much pressure to be civil and positive that one of the only acceptable ways to attack their opponent is through humor.
A classic dig came from the stiff-collared Senator Orrin Hatch of Utah. In a debate in Iowa last month, Hatch said he had a question to pitch to multimillionaire publisher Steve Forbes that would allow him to hit ''a home-run ball.''
''This usually means `hold your wallet,''' Forbes replied.
''Steve, I couldn't even lift your wallet,'' Hatch shot back.
Forbes got a chance to sting Hatch in return at Saturday's debate in Iowa, after Hatch used an answer to plug an ad that he described as a ''a fireside chat of about 30 minutes.''
''I hope the fire survived,'' Forbes replied.
Sigmund Freud's description of humor as a vehicle for expressing hostility seems especially apt when the Democratic presidential candidates get together. Laughter rarely punctuates debates between Gore and Bradley, the former New Jersey senator, and the few funny lines spring from sarcasm more than wit.
In a recent debate in New Hampshire, Gore said he was hoping for a come-from-behind victory in the state's Democratic primary Feb. 1.
''Well, you know, Al, your underdog pitch brings tears to my eyes,'' Bradley said drolly.
''Well, I hope that my upset victory brings tears to your eyes,'' Gore snapped back.
In Iowa, the Gore campaign is using a comic character - ''Corn Man,'' a volunteer ''stalker'' who dresses up like an ear of corn and hands out critiques of Bradley's farm policy - to wage psychological warfare on the usually cool and laidback Bradley. ''Real class,'' Bradley complains.
''When your opponent engages a cartoon figure,'' laughs a Gore spokesman, ''you know you are doing well.''
There's risk, of course, when amateurs try to be funny. McCain, whose humor at times has a mean-spirited edge, made a joke last year about his growing old. ''The nice thing about Alzheimer's'' McCain quipped, ''is that you get to hide your own Easter eggs.'' Last week, the New Hampshire branch of the National Right to Life Committee, which opposes McCain on campaign-finance issues, took out a radio ad accusing McCain of insulting the elderly.
McCain was unapologetic and is determined to be remembered as the funniest man in the presidential field.
