The administration of US President Barack Obama has said it will seek to block a controversial bill describing as genocide the World War I killing of Armenians by Turks.
A congressional panel on Thursday approved the resolution, paving the way for a possible vote by the House.
But Secretary of State Hillary Clinton said the administration would "work very hard" to prevent this.
Turkey voiced strong protests after the vote and recalled its ambassador from Washington for consultations. Prime Minister Recep Tayyip Erdogan said his country had been accused of a crime it did not commit, adding the resolution would harm Turkish-US relations.
Mrs Clinton - who had urged the House Foreign Affairs Committee not to hold the vote - said: "We are against this decision. Now we believe that the US Congress will not take any decision on this subject."
The resolution - approved by 23 votes to 22 by the committee - calls on Mr Obama to ensure that US foreign policy reflects an understanding of the "genocide" and to label the killings of Armenians as such.
Turkey is a major partner in US efforts to stabilise Afghanistan and Iraq, and lies on a key route taking oil and natural gas to Western markets.
Ankara accepts that atrocities were committed but argues they were part of the war and that there was no systematic attempt to destroy Christian Armenians.
During his campaign for the 2008 election, Mr Obama promised to brand the mass killings genocide.