TAMPA, Fla. — Sen. John McCain detailed his plan to solve the nation's health care crisis in a speech here Tuesday, calling for the federal government to give some money to states to help them cover people with illnesses who have been denied health insurance.

McCain's plan would shift the emphasis from health insurance provided by employers to health insurance bought by individuals, to foster competition and drive down prices. To do so he is calling for eliminating the tax breaks that currently encourage employers to provide health insurance for their workers, and replacing them with $5,000 tax credits for families to buy their own insurance.

McCain's proposal was similar to one President Bush pushed for last year to little effect. And his call for expanding coverage through market-based competition is a stark contrast from Democratic proposals to move toward universal coverage, with government subsidies to help lower-income people afford their premiums.

McCain had previously described aspects of his health plan. On Tuesday he offered new details on how to cover people with existing health problems, in a nod to the growing concerns about the difficulties many sick, older and low-income people have in getting insurance. Democrats had said his market-driven plan, by not compelling insurers to cover people with health problems, would ignore the plight of those who have trouble getting coverage.

"I'll work tirelessly to address the problem," McCain said in a speech here at the H. Lee Moffitt Cancer Center & Research Institute. "But I won't create another entitlement program that Washington will let get out of control. Nor will I saddle states with another unfunded mandate."

For people who currently get health insurance through their jobs, McCain's plan would provide a tax credit that they could apply toward a different, potentially less expensive, insurance plan tailored to their needs — and allow them to keep the same plan, and doctors, even if they switch or lose their jobs.

But Democrats and some experts said the proposal might lead some employers to stop offering health insurance, and questioned if the tax credit would cover the cost of private insurance.

Unlike McCain, of Arizona, Sens. Barack Obama of Illinois and Hillary Rodham Clinton of New York would make it illegal for health insurance companies to deny an applicant because of health status. They argue that such regulation is needed to end discrimination against those with pre-existing medical conditions.