Call him the Cassandra of Capitol Hill. For nearly two years Norman Ornstein, a resident scholar at the American Enterprise Institute, has been running around Washington auguring doom and calling on lawmakers to ponder a horrific question: What would have happened if United Flight 93, brought down in the fields of southwestern Pennsylvania on September 11, 2001, had departed Newark on time?

"We know that United 93 crashed in Pennsylvania only because it left forty minutes late," Ornstein says; otherwise its passengers would not have learned that their hijackers were on a suicide mission, and so would have had little incentive to risk storming the cockpit. Rather than roaring to earth near the town of Shanksville, Flight 93 would have continued south to Washington, where the terrorists, it is now believed, intended to guide their stolen missile into the dome of the Capitol. "Hundreds of people could have been killed," Ornstein says. Hundreds of others could have been gravely injured. "The Capitol dome is cast iron, so if the plane had hit it the way those planes hit the Trade Center, you would have had molten iron raining down on the heads of hundreds or thousands of people." In considering the potential carnage, Ornstein says, it occurred to him, "Wait a minute—what does that mean for a quorum?" The Constitution dictates that House members may be replaced only through special elections, which take months to organize. "So at the worst possible time," he says, "there's no Congress"—which means no one with the authority to declare war, appropriate money, or make laws. "What you're doing is condoning for what would be a sizable period of time a form of martial law. And when people say, 'Well, what's so bad about that?' I say, 'Two words: John Ashcroft.'"

Thanks to the passengers of Flight 93 (and the inefficiency of the airlines), Congress escaped catastrophe on 9/11. But next time, Ornstein says (and he is certain there will be a next time), it may not be so lucky: "As you think about the history of al Qaeda, they go after a target and if they don't get it, they'll come back in a couple of years." Ornstein's mission is to prod lawmakers into writing, in effect, a collective will that would prepare the federal government to handle mass casualties within its ranks.

Through endless phoning, lobbying, and writing on the subject, Ornstein has recruited enough supporters to create a blue-ribbon commission. Launched last fall, the commission is co-chaired by the former senator Alan Simpson and the former White House counsel Lloyd Cutler, and includes such political luminaries as the former congressmen Newt Gingrich and Thomas Foley. Operating under the deceptively soothing name Continuity of Government Commission, these political insiders and constitutional scholars spend their time debating macabre questions: Precisely how many House members must die to trigger a state of emergency? What constitutes a quorum if fifty senators survive a sarin attack but twenty of them are temporarily incapacitated? Worst case: who assumes the presidency if a deranged Islamist sneaks a nuclear suitcase bomb into an inaugural (Ornstein's doomsday scenario of choice), vaporizing not only the President and the Vice President but also most of the Cabinet, the Supreme Court, and Congress?

The commission's first report, released this spring, recommended ways to cope with the sudden decimation of Congress. A second report will tackle casualties in the executive and judiciary branches. Although differences among the commissioners abound, all agree that the current system threatens to leave the nation rudderless in its most vulnerable hour.

In reviewing existing law, the commission has outlined some of the more outrageous scenarios that could come to pass. For instance, the Constitution says that the House may conduct official business only when a quorum is present—currently at least 218 of the 435 members. Since the Civil War, however, the House parliamentarian has interpreted a quorum as a majority of members "elected, sworn, and living," in Ornstein's words. Ornstein finds this interpretation not only constitutionally dubious but also, in practical terms, absurd. "You could end up with, say, eight members being alive—five of them constituting a quorum," he says. Imagine a three-person quorum consisting of the ultraconservatives Tom DeLay, Ernest Istook, and Dan Burton—or of the leftists Maxine Waters, Charles Rangel, and Nancy Pelosi. How legitimate would the country consider such a body? Even more frightening, Ornstein adds, this abbreviated quorum could elect a new speaker of the House, who would then jump up the line of succession for the Oval Office. As set by the Presidential Succession Act of 1947 (which Ornstein calls "an abomination"), the line now goes from the Vice President to the speaker of the House to the Senate president pro tempore (who until two years ago was the terrifyingly dotty Strom Thurmond) and then down through the Cabinet, according to the order in which the offices were created. "You have a provision in this law," Ornstein says, "which is just mind-boggling—that if you go down to the Cabinet level to fill the presidency, the speaker can at any subsequent point bump that person and assume the office." In other words, if a catastrophe made Secretary of State Colin Powell acting President, a quorum of Burton, Istook, and DeLay could elect DeLay the new speaker, and he could elbow President Powell right out of office. Not scared yet? Assuming that the Supreme Court had also been destroyed in the blast, President DeLay would then be in a position to fill all those vacancies.

In recommending a new strategy, most of the commissioners settled on a short, simple constitutional amendment granting Congress the authority to establish guidelines for selecting temporary members in an emergency. (Making the amendment itself more detailed, Ornstein says, would increase the risk of "unintended consequences.") Congress could fashion whatever system it chose, but Ornstein—among others—favors having the nation's governors take the lead in selecting replacements. Following an attack each governor would determine whether a majority of his or her state's congressional delegation was "dead, missing, or out of service." If so, the governor would sign a proclamation to that effect; if a majority of governors signed such proclamations, each governor would make temporary appointments. As for whom the individual governors would appoint, Ornstein favors a provision like the one added to Delaware's constitution during the Cold War, whereby each elected official, before being sworn in, compiles a short list of possible replacements. In an emergency governors would pick from these lists. "So you still have gubernatorial discretion," Ornstein reasons, "but you make sure it's somebody that basically fits within the guidelines set by the former incumbent."

The commission just recently turned its attention to the issue of presidential succession, but Ornstein long ago began a dialogue with the White House about what he regards as a necessary overhaul. "Just making sure one Cabinet schnook is kept away from the State of the Union is not adequate anymore," he says. "And you've got all kinds of people in the line of succession who should not be. Look at this Cabinet—or look at the last Cabinet. Or any Cabinet where the President makes choices based on ethnic considerations or geographical considerations or ideological considerations." What's more, the Constitution stipulates that the line of succession should go from the Vice President "to such other Officers—capital O—as Congress will designate," he says. "'Officer' means an executive-branch officer. And the Constitution makes it clear that a member of Congress"—such as the speaker of the House and the president pro tem of the Senate—"can't be an executive-branch officer."

But despite the commission's labors, and Ornstein's relentless lobbying, Congress seems disinclined to take up the cause. In February of last year a House judiciary subcommittee held hearings on the subject. "It was a perfectly good hearing," Ornstein told me. "But it became clear to me during and afterward that Steve Chabot, who's the chairman of the subcommittee, really had no intention of doing more than holding a hearing ... And I think that was probably pretty much the direction he got from the speaker and the chairman of the committee." And although amendments dealing with congressional continuity have been introduced in both the House and the Senate, the amendments appear unlikely to move toward a vote anytime soon. "For the life of me," Ornstein says, "I can't understand how smart people in positions of authority and those who care about their own institutions can look at this and not say it is irresponsible for us not to take some steps to protect the country." The foot-dragging appears to have several causes. "There is some resistance to the notion of a constitutional amendment," Ornstein says, "although I have to tell you that a lot of that resistance comes from people who support amendments on abortion and flag-burning and the like." Other members cling tightly to the traditional House, a body composed entirely of elected members—distinguishing it from the Senate, to which governors may appoint replacements. Still others think in personal terms. "They think of their governors replacing them and say, 'Well, I'm not going to let him replace me,'" Ornstein says. He can understand, for example, the unease of New York Democrats at the idea of having George Pataki replace them. "But you know, what you have to say to these people is, 'You'll be dead. Consider the alternatives.'"

Therein lies perhaps the biggest problem. Unsurprisingly, most lawmakers are less than eager to contemplate their own violent demise. "To the degree that they've been willing to grapple with the dangers," Ornstein says, "their attitude is that what you have to prepare for is to make sure you can evacuate in the case of an emergency. They don't even think that the worst-case scenario is that they're all dead." Ornstein acknowledges that there's something a bit creepy about discussing the repercussions of mass slaughter in the chilly, bloodless terms of constitutional law, but he maintains that the issue is too important to ignore. "Think of a couple with small children," he says. "They go off together on some dangerous trip, without any resolution of custody issues. They basically say, 'Aw, everybody will sort it out—even though I've got a sister who will take it to court because she doesn't like my in-laws. It'll work out.' We would look at those people and say, 'How irresponsible can you get? That's really dumb.'"