Kevin White's superbly choreographed announcement that he would not seek a fifth straight term as mayor of Boston was followed quickly by the verdicts on his rule. The consensus is that the "good Kevin" the one who vanquished anti-busing leader Louise Day Hicks and was generally seen as the progressive urban reformer, lasted just over eight years, only to be replaced by the "bad Kevin," under whom blind loyalty and the building of a political machine took precedence over individual ability and the rebuilding of the city's aging neighborhoods. No judgment of the White administration will be made here. But White's remarkable tenure and the fact that he was never even considered a candidate for president tell us something quite bad about the way we do pick our presidents.

Because there are only two perishable resources in every campaign--time and money--and because the amount of money that can be spent is limited by law, time becomes the most precious resource in the contemporary presidential campaign. It is no accident that in 1975, a full year before the election, underdog and full-time candidate Jimmy Carter spent 260 days campaigning. In 1979, full-time candidate George Bush spent 328 days campaigning. For their efforts, both won the important Iowa caucuses and eventually positions with the federal government. This year, all the Democratic challengers are either full-time candidates or the next best thing to it--U.S. senators.

There are no sitting mayors, or governors for that matter, running for president. The reasons are quite simple. Unlike a senator, who is just one of 100 and therefore not personally accountable for what the Senate does or fails to do, the mayor is judged by very demanding standards. Are the streets safe? Were they plowed in February? Has the trash in the alley been picked up? The senator, with a ringing speech on education and a single vote to increase appropriations, can become a "good guy"; the mayor frequently has to decide which school to close.

Senators raise issues and make tough speeches; mayors raise taxes and make tough decisions. Mayors also make appointments to office, any one of whom, with a single sin, can bring down an administration. Recently a Senate staffer in Washington was arrested while buying heroin. The staffer's boss, the senator who had hired him, received sympathy calls. If the heroin-buyer's employer had been a mayor, the calls would have been for his resignation. In the legislative world, opponents can be demonized. A mayor cannot afford that self-indulgent luxury. The mayor, like the president, must build coalitions almost daily, and different coalitions on different issues.

For 16 years, Kevin White ran a big city. He recuited and motivated and monitored hundreds of people. He made progress and he made mistakes. Controversy swirled about him; he was accountable. He made some dumb moves and he made more smart ones. But he did not hide behind press releases and floor statements. Yet never once did Kevin White make the short list of presidential possibilities. Being a successful big-city mayor is probably the best preparation for being president. The sad part is that while it is great training, it is no stepping stone. That's what the Senate is, and it makes no sense.