The Bush administration will seek $100 million to expand a fledgling grants program to curb diabetes, obesity and asthma -- a strategy to cope with soaring health costs by preventing major chronic diseases that account for most of the nation's medical expenditures.

Health and Human Services Secretary Tommy G. Thompson said yesterday that the initiative, part of the budget President Bush is to propose to Congress in two weeks, would funnel money to perhaps a dozen U.S. cities that want to design campaigns to encourage their residents to improve their nutrition, exercise more and smoke less -- changes proven to reduce chronic ailments.

The budget being finalized by the White House will have little room to ease the strain of rising health costs on states, insurers and employers. Instead, the prevention initiative seeks to lower costs by attacking the root cause: unhealthful habits that contribute to the need for medical care.

"We're not very healthy in America," Thompson said, noting that more than two out of five Americans have a chronic disease and that those ailments are responsible for three-quarters of the country's health care spending. "This is where the big dollars are."

In a meeting with reporters, the health secretary also said he is working with administration budget officials and a few senators to provide a compensation plan for medical personnel and emergency responders who suffer complications from the smallpox vaccine. Unions, local officials and many public health experts have pressured the administration to create a separate fund to cover health costs and lost work time attributed to the vaccine, which is known for its serious side effects.

"There's some anxiety out there, and I want this to be successful," Thompson said, referring to the vaccination campaign set to begin Friday. Bush has called for inoculating as many as 10.5 million volunteers who could respond to initial cases in an outbreak, and for vaccinating the rest of the population if a biological attack occurred.

Bush first proposed $25 million for the prevention grants last year. According to HHS, the House has approved that amount; the Senate has agreed to a smaller sum. Under the expanded version, cities would propose public education campaigns and other ways to encourage healthful habits -- particularly in minority communities -- and to track whether more healthful habits work. HHS will hold conferences and conduct experiments with insurance companies to foster better coverage of preventive care and disease monitoring.

Sen. Edward M. Kennedy (D-Mass.) said yesterday that he will offer an amendment to the spending package now being debated in Congress to provide $750 million for a compensation fund, along with $850 million to help states finance their vaccination programs, the Associated Press reported.

"We can't guarantee this is going to work," Thompson said. "I just know that nothing has worked so far."