Two things happened almost simultaneously in the Democratic presidential race last weekend. New Hampshire Gov. Jeanne Shaheen announced her support of Vice President Al Gore in the Feb. 1 first-in-the-nation presidential primary. And a Newsweek magazine poll showed Gore trailing slightly behind former New Jersey senator Bill Bradley among New Hampshire Democratic voters.

Neither development came as a surprise. Shaheen has been in the Gore camp for ages; her husband, Bill, is the chairman of Gore's campaign in the state. And many other polls in the past three months have shown Gore and Bradley within a few points of each other.

What could not have been said until the governor formalized her commitment to Gore is that it is now possible, for the second election cycle in a row, that the candidate recommended by the popular incumbent in New Hampshire's highest office may be rejected by the voters of that governor's party.

That happened in 1996, when then-Gov. Steve Merrill, a Republican, ended months of flirtation with other contenders by endorsing Robert J. Dole--only to see Dole upset in the primary by Patrick J. Buchanan. A few months later, Merrill announced he would not run for reelection, setting the stage for Shaheen's victory.

It is by no means a certainty that Shaheen faces a similar scenario. Gore may well be able to win the primary. The support for both contenders is soft enough that the victory is still out there for Bradley or Gore to grab. And Shaheen is almost certain to seek a third term next year, even though she may face a stiff primary challenge because of her opposition to an income tax as the solution to the school-financing crisis in her state.

But the decline in the clout of the governor in this small state illustrates how much the presidential nomination process has changed. From Sherman Adams with Eisenhower in 1952 through John Sununu with the elder George Bush in 1988, the support of the sitting governor has been considered a major prize in New Hampshire.

But here, as elsewhere, the voters have taken the bit in their own teeth. And that is the main point of a book, "In Pursuit of the White House 2000," just published by Chatham House. In the lead essay, William G. Mayer of Northeastern University, the book's editor, and Michael G. Hagen of the University of Pennsylvania demonstrate that the nominating process has been transformed "from one in which formal party organizations and party leaders played a major role into one that is, for all practical purposes, a plebiscitary system, in which the nomination is conferred on that candidate who is most successful in winning the support of whatever activists and ordinary voters happen to show up for the primaries and caucuses."

The change began, they correctly point out, with the adoption of delegate-selection reforms by the Democratic Party in 1968, and it has been accelerating ever since. Back then, only one-third of the states even held presidential primaries. Now you can count on your fingers the number of states that do not.

This has eliminated the role of favorite-son candidates, local officeholders who led their state delegations and sought out kingmaker influence in brokered national conventions.

And it led directly to the marathon campaigns, about which the public now complains. In 1968, the average announcement of candidacy for Democrats came 142 days before the opening of their convention; 136 days for Republicans. In contrast to those five-month efforts, the average Republican campaign in 1996 began 475 days before the convention started. (There was no contest on the Democratic side and no formal announcement from President Clinton.) I don't know what the numbers will be for 2000, but they will be higher. Indeed, as a practical matter, contenders such as Steve Forbes have been running nonstop since 1996.

You can argue whether these changes are good or bad. But one other consequence clearly has been damaging: the rush to judgment forced by the front-loading of the primary calendar. Since 1984, nine of the 15 challengers to the eventual winners of the Democratic nomination have disappeared within a month after the first contest. The same thing is true of seven of the 11 Republican losers. This year, six of the original 12 Republicans quit before a single vote was cast, and several of those who remain are barely moving.

In that sense, a system that was supposed to improve voters' ability to choose the candidates themselves has worked to limit their options. Repairs are badly needed.