President Bush charged Monday that the middle class under a President Kerry would be forced to pay higher taxes to fund a government takeover of medicine.

Appearing on a campaign stage set in front of a huge "Affordable Healthcare" sign as he seeks traction for his post-convention bounce in polls, Bush made some of his most extensive remarks about health care in months as part of his advisers' plan to show concern about domestic issues before debates with Sen. John F. Kerry (Mass.). But his remarks went beyond what the Democrat has outlined, and Kerry's aides cried foul.

"I'm running against a fellow who has got a massive, complicated blueprint to have our government take over the decision making in health care," Bush said, drawing boos from the crowd in a hangar in Muskegon, Mich., where he began a bus tour in a state in which he is struggling. "His plan, if you listen carefully to what he says, would have bureaucrats become the decision makers, and that would be wrong for America."

Bush mentioned the mushrooming chaos in Iraq in passing, noting "ongoing acts of violence" and saying he understands that "hard work" remains. "It's not easy to help a country," he said.

Sarah Bianchi, Kerry's national policy director, called Bush's description of Kerry's health care plan "ridiculous -- absolutely false and baseless." Kerry's plan consists largely of tax credits, as does Bush's, and she said it "is purely designed to strengthen employer-based health care."

Kerry contends that he would end Bush's tax cuts only for those making more than $200,000 a year. But Bush told working-class Michiganders that they would be in for a tax increase to pay for a Kerry agenda that the president puts at $2 trillion over 10 years.

"So I said to him the other day, well, how are you going to pay for them?" Bush said at the Ottawa County Fairgrounds in Holland, Mich. "And he said, 'That's easy -- just tax the rich.' "

"You can't raise enough money by taxing the rich," Bush added. "Guess who he thinks is going to fill the tax gap when he can't make it with the rich." Audience members indicated it is them, and Bush said, "Yes!"

Kerry's aides say his new proposals would be paid for by rolling back tax cuts for the wealthy, cutting corporate welfare, eliminating wasteful duplicative government agencies, and instituting budget rules that would restrain spending growth and require new proposals to be paid for.

Bush usually laces his criticism of Kerry with humor, but his language Monday was harsh when he said his opponent is distorting Bush's plan to let younger workers invest part of their Social Security taxes in stocks and bonds.

"You'll hear the same rhetoric you hear every campaign, believe me," Bush said in Muskegon. " 'They're going to take away your Social Security check.' It is the most tired, pathetic way to campaign for the presidency."

The president explained the retirement system's problems by saying, "The people who aren't in good shape are the children and grandchildren in this country, because there's a lot fewer payer-inners than there are recipients when it comes to Social Security checks."

Census figures show 3.8 million more Americans are uninsured than when Bush took office. A Kaiser Family Foundation study released last week found that families are paying an average of $1,000 more out of pocket for health coverage this year than in 2000, and that 5 million fewer jobs are providing health insurance than in 2001.

The candidates' health care platforms provide one of the more significant differences of the campaign, although experts say that neither plan would seriously restrain costs.

Bush wants to make health insurance and health care less expensive for individuals and employers through two measures long sought by business -- an expansion of tax-deferred health savings accounts and federal limits on liability in medical malpractice cases. Kerry promises "affordable heath care for all Americans" and has proposed what his campaign calls twice as many health care tax credits as Bush, with the assistance targeted at small businesses and people 55 to 64 years old.

Bush twice during the day cited what he called an "independent study" that concluded Kerry's health plan would cost the taxpayers $1.5 trillion over 10 years.

The study is from the American Enterprise Institute, a Bush-friendly think tank; Vice President Cheney's wife, Lynne, was a scholar there, and one of their daughters, Liz, is a fellow. Bush aides were crowing about the study in conversations with reporters before it appeared on the conservative group's Web site.

The AEI study said Kerry's plan would increase federal spending over 10 years by $1.5 trillion, while Bush's plan would cost $128.6 billion over the same period. The study acknowledged that Kerry would provide insurance for 27.3 million Americans who lack it now, while Bush's would do that for 6.7 million people.

Cheney, beginning a week-long campaign sweep through six rural battleground states, also cited the AEI study while appearing in Ottumwa, Iowa. He, too, devoted more time than usual to health care, asserting that Kerry's plan would "break the bank" by "renationalizing the nation's health care system." Echoing Bush, Cheney predicted "across-the-board tax increases" to pay for the plan.

Kerry's running mate, Sen. John Edwards (N.C.), made sport of the Republicans' theme. "Bush is today giving a speech about health care. I hear it was a short speech," Edwards said, to laughter from the crowd of 8,000 at the Tucson Convention Center. "The best I can tell, his health care plan is to pray you don't get sick."

Staff writers David Snyder, traveling with Edwards, and Lisa Rein, traveling with Cheney, contributed to this report.

A spokeswoman for Sen. John F. Kerry called President Bush's characterization of the Democrat's health plan "false and baseless."