John F. Kerry brought his newly honed economic message here Tuesday, lambasting the Bush administration for creating a "middle-class squeeze," as the Democrat attempted to blunt criticisms that he has yet to offer a clear rationale for why he is running for president.

In a passionate speech before 800 union members here, the Massachusetts senator laid out his views on a myriad of populist issues -- from the standard of living to health care. "I'm running for president because . . . ," Kerry said repeatedly throughout the busy day of speeches and fundraisers in two competitive states -- New Jersey and Ohio.

"I believe in building up our great middle class," he told New Jersey's AFL-CIO. "I'm running for president because I want an economy that strengthens and expands the middle class, not one that squeezes it."

Kerry excoriated the administration for ignoring those who are struggling in favor of the wealthy, and for protecting pharmaceutical companies rather than consumers. He ridiculed the administration for developing a complicated tax code that he said panders to corporate America. "Our tax code has gone from 14 pages to 17,000 pages. Do any of you have your own page?" he said to laughter from his union audience. "Enron got its own a page. . . . And it looks like Halliburton got a whole chapter."

The forcefulness of Kerry's delivery and the words he chose were clearly intended to address critics in his party who privately say Kerry -- who often comes off as aloof and elitist -- has failed to excite the Democratic base and to give dissatisfied Republicans and swing voters positive reasons why they should turn to him for leadership.

"I pick up the papers some days, I read people say, 'Well, what's the campaign about? What's Kerry running for? What is the guy for?' Well let me tell you directly what it is," he told guests at rock star Jon Bon Jovi's New Jersey mansion Monday night, during a fundraiser that netted $1 million.

"I'm running for president to put America back to work. . . . I'm running for president because health care is not a benefit just for the wealthy or the elected or the connected. . . . I'm running for president because I know that we could be a hell of a lot stronger in the world if we were to secure our freedom. . . . "

President Bush, during a Rose Garden news conference Tuesday, pointed to strong economic signs and said, in comments clearly directed at his Democratic challenger, "I guess if you want to try to find something to be pessimistic about, you can find it, no matter how hard you look, you know?" Bush added, "I'm optimistic. I have seen what we have come through. We've been through a recession, a national emergency, corporate scandals, a war, and yet, our economy is incredibly strong."

Asked to respond to Bush's comments, Kerry told reporters: "We're doing better than we were a few months ago. But we don't measure a presidency by four months; we measure it by four years."

Kerry also made his most extensive comments to date on the abuse scandal at the Abu Ghraib prison in Iraq, accusing the president of underestimating "the full impact of what has happened in the world to our reputation."

Kerry advocated appointing someone of stature -- such as Robert J. Dole or Sens. John McCain (R-Ariz.) or John W. Warner -- to conduct an independent investigation. "I believe it is vital for us to prove to the world that this is really not going to be swept under the rug," he said.

Kerry was well-received at his stops in New Jersey and, later, in Ohio, where several hundred turned out in the rain to hear him. In New Jersey, he brought union members to their feet at least a half-dozen times with his speech. "He was very, very good, and I feel much better after hearing him," said Tom Fischbach, a steelworker who said the Massachusetts senator exceeded his expectations. "He said what needs to be done -- he wasn't at all mushy."

Kerry's economic message was intended to address the bread-and-butter issues of the middle class. He pledged to lower health care costs and allow the importing of lower-priced drugs, and said that he will introduce proposals to enhance after-school care for working families, and to help those struggling to get out of debt.

"The price of these deficits will not be paid for by the poor. . . . You don't make America strong by attacking the weak," he said.

"You know who the White House thinks should pay for their deficit? They think it ought to be children in Head Start, women with young babies who need nutritional help, veterans who need health care. . . . And if you think that's compassionate conservatism, then Dick Cheney is Mr. Rogers."

Meanwhile, in his home state, GOP Lt. Gov. Kerry Healey called for Kerry to resign from the Senate for missing too many votes, saying the "public is not being well served." Kerry responded that he believes he is "serving the citizens of Massachusetts" by running for president.

John F. Kerry tells union members: "I'm running . . . because I want an economy that strengthens . . . the middle class, not one that squeezes it."