But the president neither canceled nor delayed his trip to Bethesda, which was intended to highlight a program in his new budget plan called "Project BioShield."

The initiative, projected to cost $6 billion over 10 years, would speed up research into new vaccines to guard against biological or chemical attacks.

It would also authorize the administration to research and swiftly distribute vaccines for diseases such as smallpox, anthrax and botulinum toxin, without congressional approval.

"We already have the knowledge and ability to manufacture some of the vaccines and drugs we need, yet we have had little reason to do so up until now, because the natural occurrence of these diseases in our country is so rare," the president said.

"But the world changed on Sept. 11, 2001. And we've got to respond to that change."

Only in the first moments of his 15-minute speech did Bush address the space shuttle. He said America was "reminded again of the sacrifices made in the name of scientific discovery."

Role of comforter

"The seven brave men and women from the Columbia will be remembered for their achievements, their heroism and their sense of wonder," he said.

In a speech of more than 2,000 words, the president dedicated 126 to the space shuttle tragedy.

To be sure, Bush has hardly completed his role as comforter in chief.

He will speak in Houston today at a memorial service for the seven lost astronauts, eerily recalling memories of President Ronald Reagan's role in the same city at a similar event in 1986, honoring the seven crew members who perished on the space shuttle Challenger.

In a memorably stirring eulogy, Reagan vowed to continue sending shuttles into space.

"Every family member I talked to asked specifically that we continue the program - that that is what their departed loved one would want, above all else," Reagan said then.

"We will not disappoint them."