A US congressional committee on Thursday passed a resolution declaring that the World War I-era slayings of more than 1 million Armenians by the Ottomans was a genocide, a move opposed by the White House and sure to anger Turkey.
The Foreign Affairs Committee approved the resolution with a narrow 23-22 vote, but it remained questionable whether it will be taken to the floor for a full vote in the House of Representatives.
As in the past, Turkey warned that the resolution could harm relations between Washington and Ankara, a key NATO ally in the region, and has not ruled out recalling its ambassador - as it did in 2007 when the same committee approved a similar measure.
Armenian Americans have been lobbying hard to pressure President Barack Obama to follow through on a campaign promise by applying the term genocide to the massacre. But he has yet to do so, saying only that there should be a "full, frank and just acknowledgment of the facts".
Obama's administration has opposed the House resolution, saying it could disrupt ongoing reconciliation talks between Turkey and Armenia, which are strongly backed by the US.
"We've pressed hard to see the progress that we've seen to date, and we certainly do not want to see that jeopardised," US State Department spokesman PJ Crowley said Thursday.
Secretary of State Hillary Rodham Clinton telephoned the Democratic chairman of the committee, Howard Berman, to state the administration's opposition to the resolution, Crowley said. Obama called Turkish Prime Minister Recep Tayyip Erdogan Wednesday.
Turkey is vital to US interest in the region. The US uses bases in Turkey to support military operations in Iraq, and Ankara has been playing a mediating role in Middle East peace. Washington also needs Turkey's backing for tough measures on Iran over its nuclear activities.
Then president George W Bush successfully pressured the House in 2007 to not bring that resolution to a vote. Turkey had already removed its ambassador and threatened a further deterioration of relations if the measure reached final passage.
Ankara warned Thursday that this could again damage relations and had already sent representatives to Washington to lobby against the resolution.
"Turkish-US relations are experiencing their most successful period in history," Erdogan said earlier this week. "I hope that they will not be damaged by such initiatives."
Armenians contend that 1.5 million of their own were systematically killed by the Ottoman Turks in 1915. Turkey maintains the death toll was much lower and resulted from violent upheaval, not an effort to eliminate the Armenian population.
US lawmakers with a large number of ethnic Armenians in their districts, particularly in California, are among the biggest backers of the genocide resolution.
The speaker of the House, Obama ally Nancy Pelosi, has not said whether she will bring the resolution up for a full vote.