Both have proven to be disastrous choices to head the Department of Homeland Security. But that's not the only thing they share. Both were enthusiastically championed for this all-important post by Rudolph Giuliani.

As it happens, Giuliani was largely responsible for putting each man on the political map and helping launch their careers. Kerik was once Giuliani's driver. Giuliani subsequently made him his city corrections chief and eventually his top cop. Kerik's 2004 nomination as Homeland Security chief was aggressively pushed by Giuliani, which helped persuade Bush to take a flyer on nominating him. We all remember how well that turned out. Kerik's nomination promptly imploded after a host of ethical and financial problems surfaced, and Giuliani subsequently had to apologize to the president.

Chertoff, too, owes a great deal to Giuliani. When the former mayor was U.S. Attorney in the 1980s, he hired Chertoff as a prosecutor and mentored him. Chertoff sent a bunch of wise guys to the slammer, effectively launching his career, and last year, Giuliani was gung-ho about the choice of Chertoff for head of Homeland Security.

Now Republicans in the House are about to launch a searing report about Katrina that demonstrates that the choice of Chertoff has been nothing short of disastrous. As yesterday's Times puts it, Chertoff "drew some of the most scathing criticism in the report" for failing to anticipate the damage the storm would do and failing to determine rapidly that the storm had breached a major levee.

Is Giuliani to blame for Chertoff? Not really. After the Kerik fiasco, Giuliani understandably didn't appear to play a role the selection of Chertoff. Still, Giuliani wholeheartedly endorsed Chertoff. As he told the Houston Chronicle at the time: "Having already assumed a great deal of responsibility in the investigations of al-Qaida, Michael Chertoff has made clear his commitment to keeping America safe. He'll be a superb Department of Homeland Security secretary."

The fact that Giuliani championed both these men for this job should tell us something about his judgment. His presidential campaign, assuming he runs, will rest largely on the same rationale that transformed him into a national figure to begin with: He led New York in the aftermath of September 11. If you think Bush's reliance on Sept. 11 is a tad over-the-top, wait until you see Giuliani in action. He's given many, many speeches since leaving office, and in them, he likes to urge his audiences to remember Sept. 11. What Giuliani really means by this, of course, is that audiences shouldn't forget his performance in the aftermath of that day. It's not an overstatement to say that Giuliani wants audiences to see him as nothing less than the primary living, breathing embodiment of the city's -- and the country's -- ability to rally after the Twin Towers disaster.

Now, however, thanks to the implosion of Kerik and the immense failure of Chertoff, these audiences may end up remembering something else about Giuliani. It's clear that the mere fact that Rudy happened to be mayor that day -- and his undeniably admirable performance after the attack -- has not translated into an ability to recognize in people the qualities needed to carry out the job of protecting the homeland from all manner of catastrophes, man-made and otherwise. Being able to pick the right person for a job as important as this one is, of course, a rather crucial trait in a president. Giuliani's 2008 primary foes will likely do all they can to make sure that audiences don't forget this.

There's a larger point here. Both Bush and Rudy chose Kerik, and now Chertoff, largely because of one reason: They appeared to see the nature of the terrorist threat in exactly the same light as Bush did. Kerik was police commissioner on 9-11, and supposedly bonded with Bush atop the smoking rubble; Chertoff, as assistant attorney general, was widely criticized for helping implement the Bush administration's policy of rounding up hundreds of Arab and South Asian men without charges for months after the disaster.

In both cases, that narrow way of evaluating a potential head of Homeland Security led Bush, and Rudy, to overlook the enormous flaws these two men possessed -- in Kerik's case, his many ethical problems, and in Chertoff's case, his well-known lack of managerial experience. Clearly, then, a willingness to see the terrorist threat as a dire one is hardly by itself a guarantor of success in a Homeland Security chief or, for that matter, in a president. If Republicans -- and the rest of us -- keep that in mind in 2008, that could bode ill for a man who's all but certain to try to sell himself as presidential material largely on the basis of his actions in the aftermath of that terrible day.

Greg Sargent, a contributing editor at New York magazine, writes bi-weekly for The American Prospect Online. He can be reached at greg_sargent@newyorkmag.com.