An Oct. 14 article incorrectly referred to Sen. Mark Dayton (D) as Minnesota's freshman senator and to Sen. Norm Coleman (R) as the state's senior senator. Dayton was elected in 2000; Coleman, in 2002. (Published 10/15/04)

In a worst-case scenario quietly presented last month by a joint CIA-FBI agency that analyzes intelligence, al Qaeda would use weapons of mass destruction to launch multiple simultaneous attacks on the United States and overwhelm the U.S. government.

It was an extreme possibility on a menu of unknowns that had less-threatening options. All 535 members of Congress continued to work as usual until this week, when Sen. Mark Dayton (D-Minn.) shut his offices, sent his staff home and cautioned people against visiting Capitol Hill.

The surprising response by the freshman senator from Minnesota to the latest in a series of warnings prompted ridicule and a flurry of angry reactions yesterday. Mayor Anthony A. Williams (D) said Dayton's decision was "ill-informed." Minnesota's senior senator, Norm Coleman (R), called Dayton reckless. Del. Eleanor Holmes Norton (D-D.C.) compared him to the boy who cried wolf. Colleagues on both sides of the aisle whispered "paranoid."

The seat of the nation's government has been menaced by repeated threats and dangers -- shootings, anthrax, Code Orange alerts and the Sept. 11, 2001, terrorist attacks. There have been repeated security briefings from federal authorities about various and unspecific threats. But no member of Congress had fled, until Tuesday evening.

Dayton, who along with his colleagues began a preelection recess this week, was unrepentant yesterday. "I would not advise someone to visit Capitol Hill between now and the election, out of extreme precaution," Dayton said in an interview. "I would not bring my two sons to Capitol Hill between now and the election."

Dayton defended his decision, saying it would be immoral to expose his staff to risks that he himself would not be taking because of the recess. "I still believe in my soul I made the necessary and wise decision to protect my staff and constituents who might visit my office," he said.

His action came in response to a series of recent briefings given to senators on Capitol Hill by the Terrorist Threat Integration Center, a joint CIA-FBI agency that performs intelligence analysis. As part of the briefings, officials presented the alarming al Qaeda scenario, according to a U.S. government official who did not want to be identified because of the sensitivity of the matter.

"This scenario was way over the top," said the official, who described it as "fire and brimstone raining down from the skies" and "the continental U.S. up in smoke." Other government agencies, including the Homeland Security Department, had asked the joint agency to place this extreme scenario in context when describing less scary possibilities, the official said.

Dayton's reaction to the extreme possibility was ridiculous, D.C. Police Chief Charles H. Ramsey said.

"It's not based on any credible information that's come in. Nobody knows why he is doing what he is doing," Ramsey said. "It doesn't take a brain surgeon to think that the White House and the Capitol are targets. But there is no credible information about planned attacks -- nothing to set off the reaction we saw."

Rep. Robert W. Ney (R-Ohio), chairman of the House administration committee that oversees House security officials, reiterated that there was no new information to support the extreme scenario. In fact, two law enforcement officials, who declined to be identified because they were discussing classified information, said some recent intelligence indicates that the preelection threat might be lessening.

"One could generally say, 'Don't ever come to Washington for the next 10 years,' " Ney said. "One could generally say, 'Don't come to New York, L.A., Washington or Chicago for the next five years.' "

Yesterday, the corridor outside Dayton's third-floor suite in the Russell Senate Office Building was a lonely stretch of marble, with only the stray passerby stopping to read Dayton's statement on the front door that the office was closed, thanks to a recent "top-secret intelligence report."

Across the hall, Sen. Jeff Sessions (R-Ala.) poked fun at his neighbor.

"Since I assume Senator Dayton won't feel safe any time soon, I suggest that you find Senator Dayton permanent space off Capitol Hill and that you allocate his Russell Office Space to me," Sessions wrote to Majority Leader Bill Frist (R-Tenn.).

Downstairs in the cafeteria, junior staff members working for Republicans wondered aloud whether Dayton was trying to come up with a work excuse that would pay for plane tickets home for his employees. There was snickering about the rest of Dayton's staff hiding in an "undisclosed location," somewhere in the city.

In the bathrooms and tunnels of the Capitol complex, cashiers and janitorial employees had heard about the lone senator who abandoned his offices.

"It's kind of scary to me that he might know something others don't," said Thomas Jordan, 45, a general laborer who has worked on the Senate side for a year after 10 years on the House side. "We just had a general meeting today -- we're supposed to have one every other Wednesday. . . . One of the staffers happened to bring it up -- that one of the senators had gotten a little paranoid."

Democratic staff members dismissed the political speculation as ridiculous but acknowledged that they were equally baffled. "We don't have the same level of concern here," one staff member said. "If you're going to attack the Capitol complex, you'd pretty much want to do it when Congress is here."

Even the Senate sergeant-at-arms, William H. Pickle, joked to a reporter that the CIA called and "wondered what information we had that they didn't have."

At a meeting attended by more than 100 senior Hill staffers, Pickle addressed the concerns raised by Dayton's decision. He said he reassured those in attendance, telling them there was "no specific threat" even though the Capitol complex is known to be a potential target for terrorists.

Pickle said the presentation by the CIA-FBI joint agency provided "pretty sobering intelligence" of a possible terror attack on the United States before the Nov. 2 election. But he said intelligence officials last week provided a new report that "somewhat diminished the information that we previously received" while affirming the threat was "still serious."

Dayton "chose to use an abundance of caution, and that's within his prerogative," Pickle said.

Jack Danielson, Dayton's chief of staff, attended Pickle's session. He said he explained Dayton's reasoning and apologized for any "concern and anxiety."

But the apology did nothing to placate Norton, the District's nonvoting delegate to Congress and a member of the House Select Committee on Homeland Security.

"He's damaged us. He's unnecessarily panicked people across the United States," said Norton, who has often questioned the federal government's security moves in the capital. "Now we have a member of Congress who steps out and says, 'I'm going to tell you something the rest of Congress won't tell you.' That's unfair to the entire security network that is in constant communication about this place."

The Minnesota delegation, like others, was deluged with phone calls.

"I can't tell you how many phone calls flooded our office, from people who were going to come to Washington, D.C., and are now worried about whether they should visit," said Erich Mische, chief of staff for Coleman. "It was a very reckless statement and action. There is no information available that suggests that people should do anything other than visit the nation's capital."

Staff writers Dan Eggen, Spencer S. Hsu, Sari Horwitz, John Mintz and Lori Montgomery contributed to this report.

"I still believe in my soul I made the necessary and wise decision to protect my staff and constituents who might visit," Sen. Mark Dayton says.Passersby in the Russell Senate Office Building glance at a notice that says the locked office of Sen. Mark Dayton (D-Minn.) is closed because of a recent "top-secret intelligence report."