(FORTUNE Magazine) – George W. Bush can't be elected President unless he allays fears that he's a lightweight. Al Gore can't win without California. These imperatives will strongly influence the candidates' choice of running mates--and help ensure that the second spot on the ballot will matter almost as much as the first.

Bush has a high opinion of at least two governors: Frank Keating of Oklahoma and Tom Ridge of Pennsylvania. But neither man has foreign-policy expertise. For that, Bush could turn to Nebraska Senator Chuck Hagel, a Vietnam veteran who has emerged as a respected voice on foreign affairs. Hagel would give Bush some of the heft he needs.

Bush can win without California's 54 electoral votes. Gore cannot. But here's the catch: If Gore has to select a Vice President from California, he's in trouble. Although polls show Gore with a modest lead, he should already have the state nailed down given his liberal positions and the humiliating defeat Republicans suffered statewide two years ago. Both leading California Democrats have liabilities. Governor Gray Davis has been in office just 19 months. And choosing Senator Dianne Feinstein will expose the ticket to an examination of the business dealings of her husband, an investment banker. A campaign that tries to save itself with its Vice President is almost always beyond salvation.

--David Shribman