A decade ago, the kind of turbulence that hit Texas Gov. George W. Bush's campaign this week might have threatened to knock a candidate out of the presidential race. For better or worse, President Clinton has changed the rules.

Bush's highflying campaign was brought to earth over the question of whether he has ever used illegal drugs, and even some supporters believe he will be hurt by this week's events. Whether the damage is serious or long-lasting was not clear yesterday -- and the candidate quickly shifted back to his pre-turbulence posture of vowing not to answer questions on the issue.

The episode revealed a campaign that, however smoothly it was operating, could be knocked off stride by one ingenious and unanticipated question. But it also showed how a decade of scandal politics -- and the example of Clinton -- have taught politicians not to crumble when the first crisis hits a campaign.

There once was a familiar pattern when political scandal erupted: the media feeding frenzy, the campaign deathwatch and the inevitable scene in a hotel ballroom where a contrite or defiant candidate withdrew from the race. That was the way it played out in 1987 when Gary Hart was hit with allegations of marital infidelity.

But after a 1992 campaign in which Clinton weathered questions about infidelity, the draft and smoking marijuana, and then the past year in which he survived the Monica S. Lewinsky scandal, that old pattern has been replaced by something new.

"You can keep your head down and plow through it," said Republican strategist Ralph Reed, a Bush adviser, "and after you have, you're a stronger candidate because people see you're not going to be knocked out by it."

Bush took a calculated risk by reopening the issue of when, if ever, he has used drugs. It is that the public will forgive mistakes of the distant past if they are convinced a politician has learned from them -- and will not repeat them.

"I think that ultimately voters will have a sense that the governor has admitted to mistakes that were made in his youth and [that they] will fall into two camps," a Bush adviser said yesterday. "Either they respect that position or they disagree with it, in which case they'll find another candidate. And we feel far more will agree than disagree."

A poll for CNN and Time magazine by Yankelovich Partners released yesterday offers some reassurance to campaign officials that the risk is worth taking. Eighty-four percent of the poll's respondents said that, if Bush used cocaine in his twenties, it should not disqualify him from the presidency.

Bush also hopes to benefit from a public backlash against the press. "From everything we've seen, people are fairly fed up with the notion of how reporters go after this stuff and the prying into public lives," one Bush adviser said. The poll for CNN and Time underscored that view. Fifty-eight percent of those surveyed said reporters should not be asking Bush about cocaine use.

But Bush also has gambled that he can partly answer the question without definitively saying he did or didn't use drugs. What he did this week was effectively deny using drugs since 1974 (when he was 28) but then refuse to say whether he used them earlier in his life.

The danger is that, after a Clinton presidency replete with evasive answers to simple questions, Bush has created the impression with voters that he is being cute or coy rather than forthcoming. Ultimately, say some political analysts, Bush may be forced to offer a clear-cut answer to the drug question.

"I think being forthright is the key to this," one GOP strategist said. "I don't think America expects you to be a saint. They do expect you to shoot straight with them."

Bush campaign officials say their candidate is taking a much different gamble by refusing to answer detailed questions about his past: Voters may assume he engaged in behavior that never occurred. But, they say, Bush feels strongly that he must draw the line on personal questions in order to help change the climate of politics.

"We have to accept the fact that people may make mistaken assumptions," one adviser said. "But the governor has a principle, which is the rationale for this answer. He's not going to bend his principles. He strongly believes, and this is something strongly supported by sociological and psychological research, that baby boomers should not detail their mistakes to their children."

This week's furor over Bush and drugs marked the first real test of his campaign under stress. It happened suddenly and unexpectedly.

On Wednesday, Bush had been peppered with questions from Texas reporters about why he would not respond to repeated questions about drug use. Bush, in forceful terms, accused reporters of succumbing to the "game" of forcing politicians to disprove unfounded rumors. Later in New Orleans, Dallas Morning News reporter Sam Attlesey told a campaign official he wanted to ask Bush a question privately. The question was whether Bush would insist that appointees to a Bush administration be required to answer standard FBI background questions about drug use, and could he meet that standard.

Bush concluded it was a legitimate question that demanded an answer. He later told the Dallas paper he understood the question to be whether someone had used drugs within the last seven years. "I will be glad to answer that question and the answer is `No,' " Bush said.

Traveling with Bush that day were media adviser Mark McKinnon, finance chairman Don Evans and finance director Jack Oliver. But senior strategist Karl Rove was heading for New York, and Karen Hughes, the governor's communications director, and Joe Allbaugh, the campaign manager, were back in Austin. Over the next 18 hours, they were in constant communication on the phone and through e-mail as they scrambled to respond to a story that was spiraling away from them.

Later that day, as Bush and his campaign team moved from Louisiana to Virginia, they reviewed what had happened and quickly anticipated that the next morning the candidate would be asked whether he could meet the more stringent standards used during his father's administration, which rejected applicants for top jobs who had used drugs during the previous 15 years.

The next morning, the need to clarify his response to the Morning News became even more apparent. "Once we saw the Morning News story, we realized it left the impression that it could be as recent as seven years," an adviser said.

That could create the impression that Bush had used drugs well into his forties, which would undermine his declaration that he had learned from the mistakes of his youth. So Bush told reporters Thursday morning that he could have passed the 15-year test at the time his father's administration began in 1989. By the end of the day, Bush once again had closed the door on further questions about drugs -- a stance his advisers say he is determined to maintain.

"I think ultimately that resounds to his benefit, but we'll see," one Bush supporter said yesterday. But then, acknowledging that risks remain, he added, "It's a different way of handling it than has been handled before."