President Bush is trying to skewer John Kerry (search) with his own words — delighting partisan audiences with a strategy to use humor as a political weapon.

As the presidential race heats up, Bush is going for the jugular with jocularity. Hoping to hurt Kerry's campaign without looking hurtful, Bush is not the first politician who tried to strike such a balance.

"Humor can be a very effective way to deliver a negative as long as the jokes are not seen as mean-spirited," said Democratic strategist Anita Dunn of Washington. "There is an invisible line that can't be crossed — between lighthearted and poking fun to make a larger point, and something that is just plain mean."

Bush tried to walk that line Tuesday, the final day of a two-day bus tour through Michigan and Ohio. He reminded a Republican-leaning crowd that Kerry has suggested that some foreign leaders want him to win the presidency. "He just won't give us their names," Bush said as the audience hissed.

Then he quoted Kerry, in the midst of defending his claim, noting that meetings with foreign leaders can take place at restaurants in America. "I got a hunch this whole thing might be a case of mistaken identity," Bush said. He smiled as he delivered his punch line. "Just because somebody has an accent and a nice suit and a good table at a fancy restaurant in New York, doesn't make them a foreign leader."

As the laughter subsided, Bush drove home his broader point that Kerry is not suited for the presidency at a time of war. "Whoever these mystery men are, they're not going to be deciding this election," he said. "The American people will decide this election."

Bush prefers the stiletto to the ax. Both weapons cut, a senior adviser said, but one leaves less of a wound and, thus, less fallout for Bush.

But even jokes can backfire. Bush drew criticism last month for making light of the government's inability to find weapons of mass destruction in Iraq.

"Clearly, Bush isn't very good at telling jokes," said Kerry spokeswoman Stephanie Cutter. "And if only he had taken the real issues facing the American people more seriously, maybe the nation wouldn't be struggling at home and abroad as much as it is today."

Ronald Reagan used humor effectively. In a 1980 debate he sidelined Jimmy Carter's criticism with a dismissive "there you go again." He answered questions about his advanced age in a 1984 debate by saying he wouldn't make an issue of Walter Mondale's youth and inexperience.

In 1988, Texas Gov. Ann Richardson (search) joked that Bush's father was born with a silver foot in his mouth.

Bush hopes to convince voters that Kerry has a foot-in-the-mouth problem of his own.

At rallies in Michigan on Monday, he quoted Kerry as saying early this year that he had sports utility vehicles. More recently, the senator said he didn't own an SUV, only to say later, "The family has it. I don't have it."

By the time Bush had finished reciting Kerry's quotes, the audience in Sterling Heights, Mich., was in the throes of laughter.

"Now, there's a fellow who's getting a lot of mileage out of his Suburban," Bush said with a sly smile.

For weeks, Bush has reminded audiences that Kerry voted both for and against an $87 billion Iraq reconstruction bill. He doesn't bother to explain that Kerry approved of the spending, but only if Bush's tax cuts were repealed to pay for it. Full disclosure might take some sting out of Bush's mocking rebuke.

"The president must speak clearly and mean what he says," Bush said.

He uses the anecdotes to cast Kerry as a flip-flopping politician who can't be trusted with the levers of power. That's a harsh accusation, culled from cherrypicked Kerry quotes and votes and then softened by laughter.

"He's been in Washington for quite a long time. He's been there long enough to take both sides of just about every issue," Bush said in Michigan.

"He voted for the Patriot Act (search). He voted for NAFTA (search). He voted for No Child Left Behind (search). And he voted for the use of force in Iraq," the president said. "Now he opposes the Patriot Act, NAFTA, the No Child Left Behind Act, and the liberation of Iraq."

Bush's surrogates, including Vice President Dick Cheney (search), have ridiculed Kerry on similar grounds, but aides say the president is growing comfortable with the edgy gibes.

Dunn says some voters will get the joke. Others won't.

"It will be like everything else in the campaign — people who like John Kerry will see it as mean, and people who like Bush will love it," the Democratic strategist said. "And the people in the middle are not reading the papers."