Often, lesser considerations have taken precedence. Richard Nixon picked Gov. Spiro Agnew of Maryland because he was from a border state and had talked tough about law and order. George McGovern settled on Sen. Thomas Eagleton of Missouri in desperation, after several other people had turned him down. George H.W. Bush chose Sen. Dan Quayle of Indiana to make the ticket younger and more conservative. None of those choices worked out well.
Other presidents, however, have looked more to substance and seasoning. Jimmy Carter chose Walter Mondale, Ronald Reagan went with Bush, Bill Clinton opted for Al Gore and George W. Bush selected Cheney. Each had his critics, but they had in common the most important attribute: being plausible presidents. When the prospective Democratic and Republican nominees of 2008 weigh their decisions, that quality should be first among all.
The decision is particularly important for the 71-year-old John McCain, because he would be the oldest person ever to enter the presidency. Given his age and medical history, his vice president would have a higher-than-average statistical likelihood of ascending. But even the youthful Barack Obama should keep in mind that life offers no guarantees of longevity: Eight presidents have failed to live out their terms.
Familiarity with national security matters is important—now more than ever—and executive experience counts for something too. Fortunately, there are more candidates than we can list who would be reasonably prepared to take over if necessary. On the Republican side, some of the stronger ones include Secretary of State Condoleezza Rice and former homeland security secretary Tom Ridge. Among the GOP senators warranting serious consideration are former education secretary Lamar Alexander of Tennessee and Lindsey Graham of South Carolina—not to mention Joe Lieberman of Connecticut, a Democrat who often breaks with his party on issues such as Iraq.
Obama or Clinton should consider each other as a potential veep candidate. The list of logical Democrats includes Gov. Bill Richardson of New Mexico, who was ambassador to the United Nations and energy secretary, as well as Senate Foreign Relations Committee Chairman Joe Biden of Delaware. Other highly qualified prospects: California's Sen. Dianne Feinstein, the No. 2 Democrat on the Intelligence Committee; former governor and senator Bob Kerrey of Nebraska, a member of the 9/11 commission; and former Sen. Max Cleland of Georgia, who headed the Veterans Administration under President Carter.
Pay less attention to these individuals and their ideologies than to their attributes: Every name here exemplifies the qualities of experience, substance and seriousness that are indispensable in a vice president.
When this year's nominees make their choices, matters like political appeal and personal chemistry are bound to enter into their thinking. But they should start the winnowing process with the most important question: Would you trust this person with life-and-death decisions in a moment of crisis? Because at some point the next president—and the rest of us—may have to.