Sen. John McCain provided new details yesterday of how he would seek to change the nation's health care system, including ways to help the nation's 47 million uninsured.

Mr. McCain, the presumptive Republican nominee for president, said he would work to help people who lack group health insurance and those with pre-existing health problems "to get the high-quality coverage they need."

"But I won't create another entitlement program," he said in remarks prepared for delivery at the H. Lee Moffitt Cancer Center & Research Institute in Tampa, Fla.

Mr. McCain said that if elected, he would work with governors to develop a "best practice model" that states could follow to ensure people have access to health coverage.

One possible approach, he said, would be a federally subsidized, nonprofit group that could contract with insurers to cover people who have been denied insurance.

While a number of details remained unclear, he proposed "reasonable limits" on health care premiums and said "assistance would be available for Americans below a certain income level."

"We want a system of health care in which everyone can afford and acquire the treatment and preventative care they need," Mr. McCain said.

Mr. McCain's plan has some similarities to those proposed by the two Democratic candidates for president, Sens. Barack Obama and Hillary Rodham Clinton, particularly in ways to cut health care costs and improve quality.

But in some ways, the Democratic proposals are markedly different. Both Mrs. Clinton and Mr. Obama, for example, would require many businesses to offer coverage or contribute to its cost. Mrs. Clinton's plan would require all Americans to sign up for coverage, while Mr. Obama's plan would mandate coverage for children.

In his remarks, Mr. McCain criticized the idea of universal coverage, saying it would bring "tax increases, new mandates and government regulation."

He also touched on a number of details in his health proposals that have been mentioned before.

While still having the option of employer-based coverage, Americans could receive a refundable tax credit of $2,500 per individual or $5,000 per family to offset the cost of insurance, with the credit being sent directly to the insurance provider. To pay for those credits, he would eliminate the tax exemption that workers receive through their employer-sponsored health insurance, raising an estimated $3.6 trillion.

Mr. McCain also believes that people should be able to purchase health insurance across state lines, saying that creating a national market would help make "the best practices and lowest prices available to every person in every state."

"Americans need new choices beyond those offered in employment-based coverage," he said. "Americans want a system built so that wherever you go and wherever you work, your health plan goes with you."

Mr. McCain also urged medical liability reform, saying those reforms should eliminate lawsuits directed at doctors who follow clinical guidelines and adhere to patient safety protocols.

And he wants to bring greater competition to drug markets through "safe re-importation of drugs and faster introduction of generic drugs."

Some analysts have raised concerns about some of Mr. McCain's proposals.

Dr. Linda Blumberg, an economist and principal research associate at the Urban Institute, said Mr. McCain's tax break changes would threaten the group health insurance system by encouraging younger, healthier people to seek their own coverage, placing substantially increased financial burdens on older or less healthy people.

And allowing purchases of insurance across state lines undermines the ability of states to regulate health insurance markets through broader-based sharing of health care risk, she said.

Healthy people living in states with more regulation could avoid having to share in the costs associated with insuring high cost people and groups by buying insurance from a less regulated state, she said, leaving "higher financial burdens for the less healthy, and potentially less coverage as well."

The focus of all three candidates on health care comes at a time when Americans consider it a top economic concern.

A poll this month by the Kaiser Family Foundation found that 28 percent of respondents said that they or their families have had a serious problem paying for health care and health insurance as a result of recent changes in the economy. The issue ranked third behind the 44 percent reporting serious trouble paying for gasoline and the 29 percent reporting severe problems getting a well-paying job or a pay raise.

Another Kaiser poll found a big shift in independent voters' health care concerns since February, with a much larger share of respondents concerned this month with having presidential candidates talk about reducing costs rather than expanding coverage.

The poll showed "the degree to which health care is becoming a pocketbook and economic issue," said Dr. Drew Altman, the foundation's president.