(Reuters) - When President Barack Obama used the Holocaust Memorial Museum as a backdrop to unveil a new advisory panel as an early warning system for human rights crises around the world, the announcement seemed well-timed for the unfolding conflict in Syria.

But six weeks later and just days after a massacre of civilians in Syria, there is little sign that Obama´s Atrocities Prevention Board is making a mark on U.S. efforts to craft a response amid international outrage over the mounting carnage.

Although the board is only in its early stages and is still hailed by rights advocates as a valuable new weapon against state-sponsored violence, its low profile on Syria underscores the limits of Obama´s options in confronting new humanitarian crises as they arise.

More than a year after Syrian President Bashar al-Assad launched a brutal crackdown on the opposition, Obama has made clear he has no appetite for launching a new large-scale military engagement in a U.S. election year, preferring instead to rely on diplomatic and economic pressure on Damascus.

Obama´s more passive approach on Syria stands in sharp contrast to his decision to join a NATO air assault in Libya last year. That was justified largely on humanitarian grounds of averting a threatened massacre of civilians in rebel areas.

It is an awkward position for a president who has touted his human rights focus, and some critics have suggested Syria could even turn into Obama´s Bosnia - a reference to former President Bill Clinton´s initially slow response to the Balkans conflict in the 1990s.

"Inaction on Syria is going to look bad" in historical terms, said Winny Chen, head of the crimes against humanity division of Human Rights First. But rights groups themselves have yet to forge a consensus on whether intervention or arming the rebels would help or just make matters worse in Syria.

PANEL HEADED BY ´HUMANITARIAN HAWK´

In Obama´s April 23 speech at the Holocaust museum in Washington, he announced the new inter-agency advisory commission to be run out of the White House and coordinate the government´s response to crimes that "shock our conscience," such as mass killings, genocide and ethnic cleansing.

It is chaired by Samantha Power, a senior Obama adviser and outspoken expert on genocide, who is considered a "humanitarian hawk" within the administration.

The White House was tight-lipped when asked several times about the board´s activities this week.

An administration official said members had discussed Syria and would continue to do so "as long as atrocities are being committed," but played down any notion they were heavily focused on the crisis, which is being handled directly by Obama and his top advisers.

"Syria does not suffer from a lack of high-level attention, and the APB is not going to displace the other high-level policy processes that we have in place," the official said.

A humanitarian policy expert who has advised the White House agreed that Syria should not be allowed to "suck the air out of the room" in the board´s deliberations. But the expert insisted the board needed to be seen playing a significant role to cement its own legitimacy.

But that should not detract from the panel´s main goal of detecting early signs of emerging human-rights crises and driving international action before they become full-blown conflicts like in Syria, the expert added.

At the Holocaust museum event, Obama heard famed author and Holocaust survivor Elie Wiesel ask pointedly whether the world had learned anything.

"If so, how is it Assad is still in power?" he asked.

Obama reminded his audience that he was the first U.S. president to have declared preventing mass atrocities and genocide a "core national interest."

But he quickly added: "That does not mean that we intervene militarily every time there´s an injustice in the world. We cannot and should not."

It was a clear message that the use of military force against Damascus was not a viable option, and Obama has stuck to that position even as the death toll in Syria has climbed.

The White House has struggled to explain Obama´s case-by-case approach to the "Arab spring" uprisings, fears of a sectarian bloodbath that could spill across Syria´s borders and U.S. military concerns of trying to impose a "no-fly" zone on a country as well- armed as Syria.

But Republican Senator John McCain, a harsh Obama critic and 2008 presidential election opponent, remains unconvinced.

"Until we get serious about helping the Syrian people defend themselves, find safe haven, and fight back against Assad, the killing will continue, and we will be shamefully complicit, as we are now, in allowing this mass atrocity in Syria to go on and on," he said last weekend. (Editing by Peter Cooney) (© Thomson Reuters 2012. 06/01/12)