OUISVILLE, Ky. - The presidential campaign erupted into fireworks yesterday even before its traditional Labor Day kickoff, as the Republicans questioned Al Gore's credibility in a TV ad that shows him attending a Buddhist temple fund-raiser and taking credit for inventing the Internet.
''There's Al Gore reinventing himself,'' a woman says in the Republican National Committee ad that was sent to television stations yesterday and will air as early as tonight in 17 states.
George W. Bush's campaign cast the piece as ''tongue-in-cheek,'' yet it dovetailed with the Texas governor's recent focus on Gore's credibility. Bush has claimed that Gore's pledges to provide prescription drug coverage and middle-class tax cuts echo promises he and President Clinton made in 1992.
''You know why he has to say it eight years later?'' Bush asked a crowd at Butler Traditional High School here during a speech that mainly focused on his education agenda. ''Because they couldn't deliver on the promise eight years ago.''
The Democrats said the TV commercial shows that Bush broke his vow against negative campaigning in order to stop his slip in the polls.
With Gore standing silently in the background, his running mate, US Senator Joseph I. Lieberman of Connecticut, told a crowd of 2,500 in Seattle about the Republican ad, eliciting a loud ''boo.''
''Today, I'm sorry to say that Governor Bush's promise to change the tone of American politics has run into the reality of a troubled Bush-Cheney campaign,'' Lieberman said. ''These new attack ads break his promise not to launch personal attacks in this campaign and they drag us back to the worst politics of the past.''
Lieberman continued: ''It seems to me today that Governor Bush has sadly changed his tune about changing the tone.''
Two political analysts questioned the timing of the ad, but said it was within the bounds of fairness.
''The argument for Bush is still significantly an argument for change and an argument for character and an argument for trust,'' said Washington political analyst Stuart Rothenberg. ''My own view, for what it's worth, is if you can't talk about an opponent's character, you're carving out an awfully large area of what you're electing. Presumably, the person you vote to such a high office has the character you want.''
Larry Sabato, a political science professor at the University of Virginia, agreed, saying: ''Bush's argument is that Gore is a hypocrite, you can't believe what he says because what he does is different, and it's time for a change. If Americans don't accept that, he's going to lose.''
Both Sabato and Rothenberg said the ad's timing may be telling.
''I guess I'm surprised they don't wait to see what happens with the'' poll ''numbers, unless they feel like the race is slipping away or that the coverage is going so against them,'' Rothenberg said.
Sabato thought that was exactly what was happening.
''Since the Democratic convention, the Bush campaign has been in a trough that hasn't fully showed up in the polls. They desperately need to get off the defensive and on to the offensive, and everybody would agree this is on the offensive,'' the professor said.
The new ad is being sponsored by Victory 2000, a wing of the RNC now under the control of the Bush campaign.
The spot is titled ''Really'' and focuses on what Republicans view as Gore's chief weakness: his credibility, especially in the aftermath of President Clinton's deceit about his affair with Monica S. Lewinsky.
The commercial begins by showing a TV set in a kitchen as it plays a tape of Gore at the 1996 Buddhist temple fund-raiser while the vice president pledges to make campaign finance reform his number one political priority.
A woman's voice says: ''There's Al Gore reinventing himself on television again. Like I'm not going to notice. Who's he going to be today? The Al Gore who raises campaign money at a Buddhist temple or the one who now promises campaign finance reform? Really.''
The commercial then shows a clip of Gore on CNN in 1999 saying, ''I took the initiative in creating the Internet.''
The woman responds: ''Al Gore claiming credit for things he didn't even do.'' When the clip ends, the woman says, ''Yeah, and I invented the remote control. Another round of this and I'll sell my TV.''
Bush personally reviewed and approved the ad. His spokeswoman, Karen Hughes, denied it was an attack ad.
''It's a tongue-in-cheek, good-natured way of making a very important point: There is a gaping credibility gap between what Vice President Gore does and what Vice President Gore says,'' Hughes said.
She said the ad was justified given a $30 million ad blitz by the Democratic National Party during the GOP convention.
The Republican ad appeared to reflect a new sense of urgency within the Bush campaign. The Buddhist temple and Internet footage are considered some of the most potent in the GOP arsenal.
The April 29, 1996, fund-raiser at the Hsi Lai Buddhist Temple near Los Angeles has been one of Gore's biggest embarrassments. The event was controversial because it may have violated the temple's tax-exempt status, and because members of the temple were illegally reimbursed for contributions to the Democratic Party.
This month, Attorney General Janet Reno decided not to seek an independent counsel related to Gore's fund-raising.
Gore himself has joked that his biggest mistake in this campaign was his March 1999 comment on CNN: ''During my service in the United States Congress, I took the initiative in creating the Internet.'' Gore has since said he meant only that he took the lead in laying down the policy that helped develop the Internet.
The RNC's decision to air the Gore ad prompted the Democrats to change their advertising strategy.
The Democratic National Committee had plans to unveil an ad or ads attacking Bush's record in Texas, specifically his record on health care, but the committee decided to hold them.
A senior Democratic official said of the RNC commercial: ''We think this will backfire.''
Anne E. Kornblut of the Globe Staff, traveling with Gore in Seattle, contributed to this report. Material from The Associated Press was included.
