Bush administration officials say extensive planning and exhaustive preparations have been undertaken to assure rapid and effective responses in the event of a terrorist attack at the Democratic or Republican national conventions.

Appearing before a Senate committee, Health and Human Services Secretary Tommy Thompson testified on America's preparedness in the event of a catastrophic chemical, biological or nuclear attack. Although Mr. Thompson spoke in detail about the country's overall response plans, he placed particular emphasis on next week's Democratic National Convention in Boston, Massachusetts, as well as the Republican National Convention that gets under way next month in New York.

"We have made every effort to plan and be prepared for a broad range of contingencies," he said. "We have invested staff, resources and energy to coordinate with our federal, state and local partners - and with the event planners - to ensure to the extent feasible a rapid and effective response to any public health emergency that may occur. All of us hope that these two political conventions will be safe. But even if they are not, we are very prepared to respond."

Specifically, Secretary Thompson said, emergency responders, hospitals and other health care providers are boosting what has been termed "surge" capacity, the ability to deal with hundreds, perhaps thousands or even tens of thousands of casualties that could result from a terrorist attack.

In addition, he said, enormous caches of medications have been set up across the country, including in the Boston and New York areas.

"These stockpiles include large quantities of antibiotics, chemical antidotes, life support medications," Mr. Thompson said. "We call these 'push packages' and they are stationed in strategically located warehouses ready for immediate deployment."

The secretary hailed massive increases in funding for research into terrorism-related health threats in the aftermath of the September 11, 2001, terrorist attacks on the United States. For example, he said, the federal government is spending more than 30 times as much on bioterrorism related research today as it was three years ago.

Mr. Thompson said much has been accomplished, but more remains to be done. He said greater attention needs to be focused on protecting the U.S. food supply, and anticipating new strains of pathogens that terrorists could engineer for use in a biological attack.

Also appearing before the Senate Committee on Health and Education was the director of the U.S. Centers for Disease Control, Julie Gerberding, who stressed the need for a pro-active approach to public health as part of the war on terrorism.

"We need to maintain vigilance," she said. "We need to take these threats seriously. And as time goes by, without experiencing a threat, there is a tendency for people to lose interest, or focus their attentions elsewhere. So, complacency is the overarching issue we are trying to address."

Several senators echoed Julie Gerberding's words, including Republican Lamar Alexander of Tennessee. Mr. Alexander said a healthy and active imagination can help researchers and planners anticipate potential threats so that terrorist plots do not take America by surprise.