On Wednesday evening they gathered 250-strong outside the National Constitution Center, where Sens. Hillary Rodham Clinton and Barack Obama faced off in a tense Democratic debate, to shout their message:

Free Tibet.

Clinton? Obama? John McCain?

Listen to local Tibetans, and you'll hear that they're not so concerned about the name that will go at the top of the ticket or the party that will put it there. What consumes them is whether that candidate will push China to loosen its grip on their homeland.

"I support Obama, because he can bring the change," said Jorden Tenzin, 25, of Philadelphia. But then again, "John McCain said one of the first things he would do is do something about Tibet."

The Tibetans' enormous interest in politics stands in inverse proportion to their power at the polls. In the Philadelphia area, perhaps 85 Tibetans will vote in the primary next week. Fewer, actually, since many live here as "permanent residents," not citizens, and are thus not entitled to vote.

But this, they say, is their moment, a time when protests surrounding the Beijing Olympics have brought Tibet's plight to world attention.

"Our goal is to get the presidential nominees to talk about the Tibet situation," said Tsering Wangdi, 33, head of the Tibetan Association of Philadelphia. "So far we've gotten a lot of lip service from a lot of politicians."

For now, that might be all they get.

Only about 12,000 Tibetans reside in the United States, too small a voting bloc to garner much attention. And there's not much room between the candidates' positions on China's crackdown.

Clinton said she was "deeply disturbed," Obama "deeply concerned."

Clinton has called on President Bush to boycott the Olympic opening ceremonies if human rights don't improve. Obama agrees, but says a decision should be made closer to the Aug. 8 start of the Games. McCain stopped just short of such an entreaty.

"Clinton had urged President Bush not to go to Beijing," said Karma Gelek, 42, of Philadelphia. "I don't know if she means that or if it's politicized, but she did voice that, which in itself is a very good thing."

On Wednesday, the local crowd on Independence Mall was reinforced by Tibetans who arrived from New York and Washington, their vigil defined by bright colors and solemn faces. People gathered behind a photo of the Dalai Lama as Tibetan flags fluttered in the breeze. Some people wore black armbands. Others fingered dark, Bodhi-seed mala beads.

Across Market Street, on a warm, summery evening, street-corner performers strummed protest songs, and a woman dressed as Lady Liberty decried a national loss of freedom. A guy in a polar bear costume pranced and waved in opposition to Arctic drilling.

The chants of Buddhist monks competed with the whirr of TV news helicopters overhead. A little girl held up a sign that said, "China stole my country." People wondered whether the Chinese guy taking photos from across the street was a state-security agent.

Those suspicions didn't keep people from voicing their demand. When a speaker shouted, "China! China! China!" the response came back, "Out! Out! Out!"

Jambala Ruit, an engineer from Collegeville, said what he wanted from the three presidential candidates was for their interest in Tibet to become as natural and urgent as their interest in the Middle East. He listens to hear if they use words like compassion - and whether they seem to mean it when they do.

"You hear more of that from Mr. Obama and Mrs. Clinton," he said, "but I like John McCain, too."

Probably only half the members of the Tibetan Association were born in Tibet. The rest were born and raised in India and Nepal, where their parents fled after the 1950s Chinese occupation. Wangdi, the association president, spent most of his life in India and came to the United States in 1999.

"Being at the debate is very important for us," he said. "We'd like to send a message to all the presidential hopefuls, that they at least talk about Tibet. We would like to let them know there are no basic rights in Tibet."