That may be why Romney's aides sent him to the The Tonight Show last week with this instruction: Don't try to be funny.
The Republican presidential front-runner largely complied, and that worked out just fine for him. But he apparently forgot his advisers' advice the next day, when he tried to be funny on a conference call with people in next-to-vote Wisconsin.
He recounted what he called a "humorous" story about the time his auto executive father shut down a factory in Michigan and moved it to Wisconsin. Later, when his father was in a parade while running for Michigan governor, the marching band kept playing the University of Wisconsin fight song.
"Every time they would start playing 'On, Wisconsin! On Wisconsin!' my dad's political people would jump up and down and try to get them to stop," Romney said and laughed.
A joke about closing factories? In this economy? What was he thinking?
Democrats pounced on it as fresh evidence that Romney is out of touch with the economic concerns of ordinary voters.
Jokes that might be funny another time often don't pass muster under the klieg lights of a presidential campaign.
De Niro attempted satire during a New York fund-raiser headlined by Michelle Obama last month when he ticked off the names of the wives of the GOP presidential candidates and then joked that America wasn't "ready for a white first lady."
Donors roared their approval. But by the next morning, Gingrich was calling the racial reference to the Republican wives "inexcusable" and the chastened Obama campaign was labeling the actor's comments "inappropriate."
De Niro at first declined to comment but ended up apologizing - sort of.
"My remarks, although spoken with satirical jest, were not meant to offend or embarrass anyone, especially the first lady," he said in a statement.
President Obama, for his part, has had better luck using humor to deflect questions about his own vulnerabilities, real or perceived.
During a St. Patrick's Day reception last month, Obama was presented with a certificate of Irish heritage by the Irish prime minister.
"This will have a special place of honor alongside my birth certificate," Obama deadpanned, deftly sending the message that any lingering doubts about where he was born were nothing but a joke.
Sometimes, humor can come back to bite a candidate long after the laughs have faded.
In 2004, when Romney was Massachusetts governor, he took a jab at the wealth of that year's monied presidential candidate, Democratic Sen. John Kerry.
"There's a senator from my state, you may have heard, that wants to get elected president," Romney said at a Republican Governors Association dinner. "And I don't know why he wants to do that because, of course, if he won he'd have to move into a smaller house."
It may have been funny then, but the joke boomeranged when it resurfaced on the Internet last week just as Romney was trying to combat an elitist image.
Perry, whose Republican presidential campaign quickly foundered in the primaries, took a big step toward rehabilitating his image with his appearance last month at a Washington dinner for journalists and their guests.
He got plenty of laughs when he joked that his time as the GOP front-runner had been "the three most exhilarating hours of my life."
He perfectly skewered Romney by quipping that during the GOP debates, he had been tempted to turn to his rival and ask, "Pardon me, do you have any Grey Poupon?"
Getting off a few well-rehearsed jokes - often written by someone else - is generally less challenging than displaying pitch-perfect humor day after day amid the grind of campaigning. Perry's jokes, for example, were written by GOP speechwriter Landon Parvin.
But even some of the most carefully thought-out jokes just aren't funny in the end.
Take President George W. Bush at a White House Correspondents Association dinner in 2004. He narrated a slide show that included a photo of himself hunting around in the Oval Office and then quipped, "Those weapons of mass destruction got to be somewhere."