Reinvention represents a familiar plot line in American politics: The once-confident front-runner reemerges as the self-proclaimed underdog. The cloistered incumbent suddenly becomes the guy next door. The Washington insider sheds coat and tie, picks up a drawl and sounds the note of a resentful outsider.

Last week, hoping to extract his campaign from what one Democrat called "a horrible swamp," Vice President Gore tried all three.

Gore's abrupt decision to shift his campaign headquarters from Washington to Nashville, to jettison his top pollster and to challenge rival Bill Bradley to a series of debates was part symbol and part substance. The moves reflected not only his concern about the growing strength of Bradley's campaign, but also his belief that his campaign had become dysfunctional in the hothouse environment of Washington.

What was equally remarkable about Gore's announcement, however, was the timing of it all, coming four months before the first caucuses in Iowa and the first primary in New Hampshire. If any further evidence were needed that the campaign of 2000 is operating to a set of rules and a political clock never before seen, Gore's effort at reinvention should prove it.

Presidential front-runners usually wait until they lose a contest before tearing up their script. Gore acted on the basis of bad polls, negative news coverage and slipping fund-raising -- the elements that together have been dubbed the "invisible primary" that takes place the year before a presidential election.

"This is the cycle where the invisible primary has been treated as more important than the real primary," said Republican consultant Mike Murphy. "Gore is worried that a devastating loss in the preseason of perception will lead to a real loss in Iowa and New Hampshire."

Gore's announcement will mark the last week of September as the most significant week to date in the campaign, the moment at which the Democratic race took on a new shape and, for Gore, the hope for a fresh start after a summer of missteps. But there was much more than Gore last week to signal an intensifying presidential campaign.

On the Republican side, former vice president Dan Quayle shuttered a campaign that had appeared doomed for months, opening the door slightly for Steve Forbes to emerge as the conservative of choice. Arizona Sen. John McCain formally launched a candidacy that had been gaining altitude for weeks, partly on the strength of a best-selling memoir of life in a Vietnamese prison camp.

Texas Gov. George W. Bush, maintaining cruising speed as the GOP front-runner, announced that his campaign had scooped up a record $56 million as third-quarter spending reports were made public. But after proclaiming itself a frugal beer-and-peanuts operation, Bush's campaign also was revealed as perhaps the freest-spending presidential campaign in history.

Of equal significance was Bush's decision to distance himself from the Republicans in Congress, sounding a populist note of criticism over their budget priorities by saying they should not "balance the budget on the backs of the poor." This declaration of independence clearly rattled Gore and the Democrats, and one Republican dubbed it Bush's "Sister Souljah moment," a reference to Bill Clinton's attack on a rap singer in 1992.

Meanwhile, Gary Bauer, the candidate of the Christian right and "family values," found himself forced to denounce as scurrilous charges from others once in his campaign that he was spending too much time behind closed doors with a young, female aide.

On the Democratic side, Bradley unveiled a $65 billion-a-year plan designed to move the country toward near-universal health care coverage. The proposal represented a risky reaffirmation of the federal government's role in health care after the demise of President Clinton's plan in 1994. It also represented the first installment on Bradley's promise to run a campaign -- and a presidency -- of boldness and big ideas, not, as he suggested of Gore, timidity and bite-sized issues.

And for sheer entertainment, there were Warren Beatty and Jesse Ventura. Beatty, at a glittery dinner in Los Angeles, excoriated the Democratic Party for abandoning its liberal heritage to worship at the altar of corporate campaign contributions while threatening to reinvent himself as a presidential candidate if Gore and Bradley didn't pay attention.

Ventura, the Reform Party governor of Minnesota, found himself on the defensive after giving an interview to Playboy in which he dumped on organized religion as something for the "weak-minded."

All in all, it was enough to exhaust even the hardiest of political junkies. "The velocity of this is incredible," said Bill Carrick, a California-based Democratic strategist.

Now the question is, what next?

The overriding issue is whether Gore can successfully reinvent his campaign. Last year he fought successfully to drive most of his potential rivals out of the race. But the consequence of that strategy became clear when Bradley proved to be a credible fund-raiser and a skillful candidate. Gore is paying the price of allowing the Democratic nomination fight to become a one-on-one race so early.

"The remarkable thing is that Bradley has managed to do this with four months to go before the first primary," said William Mayer, a political scientist who has written extensively about presidential primaries.

Given Bradley's growing credibility, Democratic analysts said what Gore did last week, however belatedly, was crucial to his hopes of winning the nomination.

"The race in which Gore now finds himself is not the race for which he prepared," said Democratic pollster Geoff Garin. "What he's done this week is an honest and important recognition of that fact. He's given himself a much better chance to turn things around and run a campaign that is better suited to the challenge he faces."

But having made the cosmetic change of a new Zip code for his headquarters and the more substantive decision to engage the man he studiously avoided for most of this year, Gore must reckon with the risks of his new strategy.

In an earlier shift, he moved up his formal announcement by several months in an effort to step out of Clinton's shadow and establish himself independently, with little to show for it. If this latest effort does not produce visible change, he could be in even deeper trouble by the end of the year.

Gore and his advisers have promised to engage Bradley at every turn. But first they must agree on a consistent line of attack.

Is Bradley moving dangerously to the left, as many Gore advisers suggest, pointing to health care or gun registration or opening the 1964 Civil Rights Act to include discrimination on the basis of sexual orientation? Or is he really a closet Republican who supported school vouchers and, as Gore told the Los Angeles Times last week, Reaganomics?

"Either Bradley is a faithless, disloyal Democrat who doesn't share the fundamental values of the party, or he is a pandering, left-wing kook," said one Democratic strategist. "He can't be both. They have to settle on what they want to say to win the nomination."

Campaign advisers say the left-right question is less relevant than the issue of character and consistency. Their strategy appears designed to undercut a Bradley campaign built as much on style and leadership as on the specifics of this issue or that. Gore strategists argue that Bradley is a man who is reinventing himself after 18 years in the Senate and two years out of politics. They say they will focus on areas of inconsistency between Bradley the senator and Bradley the presidential candidate.

Equally important, they say, will be an effort to portray Bradley as someone whose talk of big ideas belies a record of more modest achievement in the Senate and as a Democrat who ducked the toughest fights. "The better case for Gore to make," said Garin, who is not working for either candidate, "would be about his record of taking sides, getting in the thick of a fight and being willing to see it through."

Bradley spokesman Eric Hauser said the changes Gore is making won't throw his candidate off stride. "We've had a strategy in place for a long time," he said. "We're going to continue to follow it." Answering criticism from the Gore camp, he added, "Bradley . . . has a very good record on issues that are incredibly important to Democrats." But he added, "This agenda is not driven by an ideological spectrum, it's driven by the problems and opportunities Bradley sees and [what he] wants to accomplish."

For all the talk of staff changes and a new address for Gore headquarters, the real answer to Gore's campaign may lie with the candidate himself. Gore and his advisers believe he has become a more comfortable and appealing candidate, but there is still work to be done. Gore must answer doubts voters have about his leadership skills and project the kind of warmth many voters believe is missing in his personality.

Supporters and advisers see Gore's decision to shake up his campaign as evidence that he is wrestling personally with why voters see him the way they do. "It comes down to one thing," said one Gore supporter. "Al Gore is peeling away the layers of himself to see what's at his core."

Gore and Bradley have agreed to participate in a televised town meeting in New Hampshire on Oct. 27, but before that comes a major test of strength when the two battle over the endorsement by the AFL-CIO. Gore hopes to win labor's backing when union leaders meet in Los Angeles in a week, but Bradley is working feverishly to persuade the unions not to endorse right now.

Privately Gore campaign officials say they see the nomination contest as a two-state battle: Iowa and New Hampshire. They remain confident about winning Iowa, but obviously are worried about New Hampshire, where Bradley's support among independents, who cannot vote in most other Democratic primaries, represents a big advantage. "If Gore wins New Hampshire, it's over," one Gore supporter said. "If Bradley wins it, we've got another six weeks."

That means the race turns to California, New York, Ohio and several other states on March 7, and possibly to the South a week later. "The odds are with us," a Gore campaign official said.

Gore's campaign shake-up was designed to refocus his campaign and the coverage of the Democratic race and to put more pressure on his rival. But even many Gore supporters know that more than ever, as one put it: "This election is about Gore now."

The Republican race is a study in contrast, with a field of candidates that continues to dwindle, and with the other candidates mostly waiting for Bush to make a mistake. Bush continues to run a controlled offense, keeping himself generally out of danger.

After three months on the campaign trail, he is sticking with the stump speech he unveiled on his first trip to Iowa. He plans the second of three education speeches Tuesday in New York, and as his criticism of Congress last week showed, he will pick his spots to reinforce the message that his brand of conservatism represents a break from the Gingrich era of the mid-1990s.

Meanwhile, he will begin to shift his time from fund-raising to deepening a national political organization, while avoiding his opponents -- unless attacked on the air by Forbes, who yesterday challenged Bush to debate him.

"What we're waiting on here is for Forbes to start the war," said one Democratic strategist, echoing the views of many Republicans. "We've seen the previews, we just haven't got to the ad wars yet."

But for now, a Democratic race that once looked like a walk-away for the vice president continues to overshadow a Republican contest that many once thought would be the most competitive in a dozen years. Such are the vagaries of the campaign of 2000.