Most of the time, Barack Obama seems like he's boxing in the wrong weight class. But on Monday in Fort Dodge, Iowa, he delivered an unscripted jab that was a beaut.

At a news conference, the Illinois senator was asked about Hillary Clinton's attack on his qualifications. Making an economic speech in Knoxville, Iowa, earlier that day, the New York senator had touted her own know-how, saying that "there is one job we can't afford on-the-job training for -- that's the job of our next president." Her aides confirmed that she had been referring to Obama.

Pressed to respond, Obama offered a zinger feathered with amused disdain: "My understanding was that she wasn't Treasury secretary in the Clinton administration, so I don't know exactly what experiences she's claiming."

Everybody laughed, including Obama.

It took him nine months, but he finally found the perfect pitch to make a trenchant point.

Her Democratic rivals had meekly gone along, accepting her self-portrait as a former co-president who gets to take credit for everything important that Bill Clinton did in the '90s. But she was not elected or appointed to a position that needed Senate confirmation. And the part of the Clinton administration that worked best -- the economy, stupid -- was run by Robert Rubin. Hillary did not show good judgment in her areas of influence -- the legal fiefdom, health care and running oppo-campaigns against Bill's galpals.

She went on some first-lady jaunts and made a good speech at a U.N. women's conference in Beijing. But she was certainly not, as her top Iowa supporter, former Gov. Tom Vilsack, claimed Tuesday on MSNBC, "the face of the administration in foreign affairs."

She was a top adviser who had a Nixonian bent for secrecy and a knack for hard-core politicking. But if running a great war room qualified you for president, Carville and Stephanopoulos would be leading the pack.

Obama's one-liner evoked something that rubs some people the wrong way about Hillary. Getting ahead through connections is common in life. But Hillary cloaks her nepotism in feminism.

"She hasn't accomplished anything on her own since getting admitted to Yale Law," wrote Joan Di Cola, a Boston lawyer, in a letter to The Wall Street Journal this week, adding: "She isn't Dianne Feinstein, who spent years as mayor of San Francisco before becoming a senator, or Nancy Pelosi, who became Madam Speaker on the strength of her political abilities. All Hillary is, is Mrs. Clinton. She became a partner at the Rose Law Firm because of that, senator of New York because of that, and [heaven help us] she could become president because of that."

The Clinton campaign in Iowa is in a panic. Obama has been closing the gap with women and her ginning up of gender has lost her male votes. Speaking around Iowa this week, Obama made the point that his exotic upbringing, family in Kenya and years as an outsider allow him to see the world with more understanding and helped form his judgment about resisting the Iraq war.

"I spent four years living overseas when I was a child living in Southeast Asia," he said. "If you don't understand these cultures, then it's very hard for you to make good foreign-policy decisions. Foreign policy is all about judgment."

President Bush is not so enamored of Obama's foreign-policy judgment. He gave a plug to Hillary on ABC News on Tuesday night, calling her a "formidable candidate," even under pressure, who "understands the klieg lights."

Asked by Charles Gibson about Obama's offer to meet without preconditions with leaders of Cuba, Venezuela and North Korea, W. declared it "odd foreign policy."

Laura Bush also gave Hillary a sisterly -- and dynastic -- plug when she told the anchor that living in the White House and meeting people everywhere would be "very helpful" to a first lady trading up.

Though he did not mention the quick "color me experienced" trip Hillary took with some Senate colleagues to Iraq and Afghanistan before she started running, Obama might have been thinking of it when he mocked Kabuki congressional junkets: "You get picked up at the airport by a state convoy and a security detail. They drive you over to the ambassador's house and you get lunch. Then you go take a tour of some factory or some school. Children do a native dance."

Hillary pounced, knowing that her chief rival's foreign policy resume is as slender as his physique, once more conjuring a childish Obama. She brazenly borrowed Republican talking points, even though she accused John Edwards of "throwing mud" that was "right out of the Republican playbook."

"With all due respect," she told a crowd in Iowa. "I don't think living in a foreign country between the ages of 6 and 10 is foreign-policy experience."

But is living in the White House between the ages of 45 and 53 foreign-policy experience?

Maureen Dowd is a columnist for the New York Times.