CRAWFORD, Tex., Dec. 27 -- The discovery of mad cow disease in the United States could shift the political landscape at the start of President Bush's reelection year by injecting uncertainty into a fragile economy and drawing scrutiny to his handling of an industry that was a financial and political ally in the last election, analysts in both parties said yesterday.

White House officials had sounded ebullient as they headed into the holidays at a time when economic indicators were turning up, Saddam Hussein was in captivity and a new Medicare law had just been signed. Now, the administration will start 2004 under the type of sudden economic threat that Bush aides had expected would come only from a terrorist attack.

"Life is just not as good as December was for the president," Republican pollster Whit Ayres said.

Bush has closer ties to ranching than to any other industry besides oil, and Democrats seized on this new avenue for attacking Bush as a captive of business. Howard Dean, the front-runner for the Democratic nomination, said that it showed "the complete lack of foresight by the Bush administration once again."

Dan Glickman, agriculture secretary under President Bill Clinton and now director of Harvard University's Institute of Politics, said the White House has just weeks to develop a plan for more rigorous livestock tracing and testing. He suggested that Bush bring together representatives of science, consumers and the industry in early January -- a time when his aides had hoped to be focused on the State of the Union address.

"This will require very aggressive, proactive solutions coming from the administration," Glickman said. "You cannot monkey around with this. This is a big potential problem."

Hysteria over mad cow disease in Britain in 1996 helped bring down the Conservative government of Prime Minister John Major, who was accused of hiding the truth and failing to enforce regulations. Bush's aides sensed the potential political peril of Wednesday's announcement and said they had used the British experience as a case study of what not to do. Aides distanced Bush from the news and put Agriculture Department officials in front of cameras to give information that they hoped would reassure consumers, the industry, the markets and other countries. Nevertheless, more than two dozen nations have banned the import of U.S. beef.

Bush has been silent about the announcement that bovine spongiform encephalopathy, the degenerative brain affliction that is known as mad cow disease and is fatal in its human version, had been discovered in a Holstein raised in Washington state. The only time Bush has been seen publicly in the past five days was when he traveled Friday from Camp David to his 1,600-acre ranch here for New Year's week. His only public words were a prerecorded radio address broadcast Saturday calling for prayers for the armed forces.

Aides said they concluded they had a better chance of bolstering public confidence if they made it clear that the crisis was being handled by experts, rather than allowing Bush to appear to be grandstanding.

David Winston, a pollster who advises House and Senate Republicans, said he sees a "9/11 dynamic" in which the public will not blame Bush for the event but will judge him on his response to it.

Administration officials said their strategy is to try to calm the public and overseas governments by providing information as quickly as possible, and to try to maintain credibility by announcing information before it leaked to the markets or reporters.

Alisa Harrison, press secretary of the Department of Agriculture, said officials have continually updated a mad cow response plan that includes an incident command team to coordinate the investigation. The plan's communications section drew on Federal Aviation Administration techniques for handling the phone calls that flood in after a plane crash.

Harrison said USDA's two guiding principles are: "Keep the public informed of any new developments as soon as we know them to be true. Use science to guide our decision-making regarding the risk to public health."

Seeking to protect exports, the USDA used webcasts of its briefings to reach overseas reporters, and the administration launched a diplomatic offensive that included calls by Agriculture Secretary Ann M. Veneman to leaders of Canada, Japan, Mexico and the Philippines. Two senior USDA officials flew from Washington to Tokyo on Saturday and plan to visit Seoul and perhaps other beef customers before returning.

Bush donned a cowboy hat when he spoke last year to the annual convention of the National Cattlemen's Beef Association, and livestock interests have been among his most reliable supporters. The Center for Responsive Politics found that 79 percent of the livestock industry's $4.7 million in contributions for the 2000 elections went to Republicans. Of the $1.1 million the industry has given so far for next year's election, 84 percent went to the GOP.

Sen. Charles E. Schumer (D-N.Y.), who has been seeking a Meat Traceability and Safety Act, called the current standards "another example of the White House doing what industry wants, rather than what the consumer needs."

Dean, in an interview Friday with the Associated Press, said that the mad cow discovery "is something that easily could be predicted and was predicted" and that the administration could have softened the blow by setting up a system that provided "instant traceability." He called for "instant traceability" of meat and a federal economic aid package for the industry.