CHICAGO - The worldwide eradication of polio is unachievable and efforts should be abandoned, a senior federal health official said Saturday.

D.A. Henderson, who led the global campaign to eradicate smallpox 20 years ago and is now the government's most highly placed bioterrorism expert, roiled a scientific meeting here by proposing that the labor-intensive $2 billion effort against polio be rolled back and routine immunization resumed indefinitely.

The Centers for Disease Control and Prevention reacted swiftly and negatively to Henderson's proposal.

"To stop now would be snatching defeat from the jaws of victory," said CDC immunization expert Stephen Cochi.

Polio is a crippling, sometimes fatal disease that largely affects children. The last case in the United States occurred in 1979.

When the worldwide campaign was launched in 1988, polio was still circulating freely in 125 countries. At the end of 2001, that had been reduced to 10 countries in the developing world. The CDC hopes to announce in December that the virus has been confined to five countries.

The World Health Organization's original goal was to record the last case of polio before the end of 2000, monitor the situation for several years and then declare the world polio-free by 2005.