SAN FRANCISCO -- It was supposed to be on a "Journey of Harmony," but the Olympic torch celebrating the Beijing summer games slinked into this city before dawn Tuesday, dogged by controversy here and abroad.

As activists and police readied for a chaotic torch relay expected to produce mass demonstrations and arrests on Wednesday, China stood defiant in the face growing criticism of its human-rights policies.

The Eastern superpower has downplayed protests -- many by pro-Tibetan activists -- that have aimed to snuff out the Olympic flame and has ignored a chorus of calls for a boycott of the games' opening ceremony.

On Tuesday, International Olympic Committee officials in Beijing suggested the possibility of cutting short the torch's odyssey, abbreviating the list of 19 countries it is scheduled to visit in the run-up to the Aug. 8 opening ceremony. Officials said they might even consider scrapping the international portion of the torch relay for future games.

"I'm definitely concerned about what has happened in London and in Paris," said Jacques Rogge, president of the International Olympic Committee.

The flame embarked in March from ancient Olympia in Greece on an 85,000-mile, six-continent journey -- one of the most ambitious torch relays in the history of the Olympic Games.

China chose the slogan, "Journey of Harmony." Despite the recent public-relations fiasco, Beijing officials insisted Tuesday there be no route changes after the flame leaves San Francisco.

"No force will disrupt the torch relay," said Sun Weide, a spokesman for the Beijing organizing committee.

Chinese-Americans in San Francisco echoed those sentiments Tuesday, saying they would cheer the torch Wednesday in the face of protest. Organizers say they expect more than 15,000 to wave banners in support of Beijing.

"We're going to show the world that San Francisco stands behind China," social worker Citania Tam said as she walked in this city's Chinatown. "We're going to be the anti-demonstrators."

This normally free-spirited city was tense Tuesday. Tibetan activists and other anti-China protesters held symposiums and rallies that included speeches by Hollywood actor Richard Gere and Nobel Prize-winning South African Archbishop Desmond Tutu.

At least one Bay Area torchbearer has dropped out of the event, citing safety concerns, officials say.

Meanwhile, Mayor Gavin Newsom insisted that changes to the torch relay's route could come at any time -- even after the scheduled start of the event at 1 p.m. Wednesday. While police said they expected as many as 6,500 protesters, an organizer for the Coalition to Save Darfur said that it already had rallied 2,100 supporters, double the original estimates. Newsom said he expected "tens of thousands" to witness the event, which will be monitored by hundreds of police.

The mayor met with protesters Tuesday and later said he had advised against threatening the torch: "Nothing gets in the way of a movement more than doing something to take you away from your message ... I am not over-promising that this is the Summer of Love. (People) can peacefully disagree."

The torch, en route from Paris, touched down in San Francisco at 3:40 a.m. under heavy security and was promptly whisked to an undisclosed location, officials said. There were no protesters on hand, just a few dozen supporters.

Within hours, the first of the day's anti-Beijing protests began. Waving Tibetan flags, more than 500 supporters of a free Tibet gathered near City Hall to condemn China's violent response to dissent there. The crowd sang the Tibetan national anthem and chanted "Team Tibet!"

When one woman began weeping about deaths in Tibet, a dozen television cameras crowded in to capture her words.

Later, Tutu said in a speech that he supported the protests because it showed the people cared about events in far-off Tibet.

"I'm thrilled myself that people care as much as they've shown they do."

The relay has drawn a wide cross-section of activists -- not just activists for Tibet but those protesting China's support of Sudan and Uighur Muslims who want more freedom for their kinsmen living in western China.

But it is the Tibetan activists who have gotten the most mileage out of the relay stops, stating their decades-old grievances on a highly visible world stage.

Scholars of Tibetan history have expressed concern that some of the more daring stunts of the activists, such as attacking the torch with fire extinguishers and scaling the Golden Gate Bridge to unfurl banners, will ultimately backfire on Tibetans, whose country was formally annexed by Communist China in 1951.

"These demonstrations are all about shaming the Chinese," said Andrew M. Fischer, a Tibet scholar at the London School of Economics. "But they play into the hands of the hard-liners in Beijing who can accuse the activists of spoiling the Olympics. ... It's turning into an anti-China thing that whips up nationalist sentiments."

Some activists insist they don't want trouble.

"We plan to be loud and aggressive," said Allyn Brooks-LaSure, a spokesman for the Save Darfur Coalition, which says it hopes have 2,100 supporters at the relay. "We can be effective and get a message to Beijing without being disrespectful or disruptive."

This being San Francisco, there are, of course, events that could ease the tension. A nude torch relay is set to begin just before the official event.

Glionna reported from San Francisco and Demick from Beijing. Staff writers Tim Reiterman and Richard Paddock also contributed from San Francisco.