DENVER — The presumptive Democratic nominee for vice president, Senator Biden of Delaware, shed the traditional attack dog role yesterday in favor of a tearful appearance in front of delegates from his home state and an empathetic exchange with women facing economic hardship.

“This is a great honor being nominated vice president of the United States,” Mr. Biden told Delaware delegates at a breakfast in Littleton, Colo., according to video posted on the Web by ABC News. “I’m proud of it. I don’t mean in any way to diminish it. But it pales in comparison to the honor that I’ve had representing you. … I apologize for getting a little emotional,” he said, as he wiped tears from his eyes.

Noting a contingent of the national press corps on hand, Mr. Biden said, “I don’t care what they think. … I wish we could have done this in private, because you know, I don’t know whether I would have made it through a lot of the tough times in my life without you guys.”

Mr. Biden has faced more than his share of difficulties since he was elected to the Senate in 1972 at age 29. Later that year, his wife and infant daughter were killed in a car accident that also injured his two sons. In 1987, he dropped out of the Democratic presidential race following a series of ethical flaps, including his plagiarizing of a speech from a British politician. Less than a year later, Mr. Biden had emergency surgery to repair two life-threatening brain aneurysms and was out of the Senate for seven months.

At a forum in Denver yesterday staged by the campaign of the presumptive Democratic nominee for president, Senator Obama of Illinois, Mr. Biden and Mr. Obama’s wife, Michelle, and four female governors, met with four women who suffered economic setbacks. One of the governors and one of the invited women had abruptly lost their husbands. Another woman said she was presently suffering from a brain aneurysm. Nearly all said the government needed to guarantee health insurance to all Americans.

“Right now, we’re living in the world as it is and we are settling,” Mrs. Obama said, in coverage of the event monitored via CNN. “There’s no reason why we can’t have universal health care in this country. There’s absolutely no reason why we can’t do that. … As somebody who’s worked in the health care profession, it is something that would save this country billions and billions of dollars, if you think about all of the preventative medicine that is not going on.”

Mrs. Obama also promised that her husband would “invest billions” to upgrade America’s education system. “There is absolutely no reason why United States shouldn’t have the best education that this planet can offer. … The money is there,” she said.

When it came time to discuss how the presumptive Republican nominee, Senator McCain, might deal with these issues, Mrs. Obama deferred to Mr. Biden. “I don’t know that I can tell you what his opponent will do,” she said, smiling a bit and playfully pointing her microphone at the senator from Delaware.

Mr. Biden responded with a frank warning about the likely response to the talk of spending billions more on health care and education. “Look, you know what’s coming, folks, you know what’s coming from the Republicans,” he said. “You’re going to see on some of the shows after this is all over that ‘Joe Biden, Michelle Obama, four distinguished governors, four incredible women with a story, all they talked about was how we’re going to spend more money. It’s typical tax and spend Democrats. …’ They’re going to try to scare the rest of America into the notion that we are going to go well beyond our economic reach.”

Referring briefly to Mr. McCain as “my friend John,” Mr. Biden said universal health care could be achieved simply by rolling back $100 billion in “tax breaks” Mr. McCain and other Republicans support for American families making more than $464,000 a year.

“What is the greater obligation of the country, to give some very, very wealthy people who are good people an additional $100 billion in tax cuts, or provide health care for every American and solve every story you heard up here?” Mr. Biden asked.

Though Mr. Biden seemed to contradict Mrs. Obama by using the $100 billion price tag, he also declared flatly that better preventive care would save money. However, medical researchers who have looked at the issue say that is far from certain.

“Sweeping statements about the cost-saving potential of prevention, however, are overreaching,” three researchers who studied the issue, Joshua Cohen, Peter Neumann, and Milton Weinstein, wrote in a February article in the New England Journal of Medicine. “Although some preventive measures do save money, the vast majority reviewed in the health economics literature do not.”

Studies have shown that some efforts, such as incentives to stop smoking, are highly cost effective, while widespread screening programs, such as tests for prostate cancer, often drive up costs by prompting unnecessary and sometimes counterproductive treatment.

During the economic forum, the sharpest jab at Mr. McCain came not from Mr. Biden, but from Governor Napolitano of Arizona, who alluded to the presumptive Republican nominee’s recent inability to recall precisely how many homes he owns.

“You may have noticed John McCain’s from Arizona,” Ms. Napolitano said. “I just want to correct a misimpression. … Most of us have only one house. … I live in my condo.”