A U.S. congressional panel defied President George W. Bush on Wednesday and approved a measure calling the killings of Armenians early in the last century "genocide." Bush had warned this would damage U.S. goals in the Middle East.

The measure that would recognize the killings of Armenians as a genocide had been strongly opposed by Turkey, a key NATO ally that has provided support to U.S. efforts in Iraq.

The House Foreign Affairs Committee's 27-21 vote now sends the measure to the full House floor — unless the Democratic leadership reverses course and heeds Bush's warnings.

Bush and other senior officials had made a last-minute push to persuade lawmakers on the House of Representatives' Foreign Affairs Committee to reject the measure.

"Its passage would do great harm to our relations with a key ally in NATO and in the global war on terror," Bush said hours before the vote.

The dispute involves the killing of up to 1.5 million Armenians by Ottoman Turks around the time of World War I, an event widely viewed by genocide scholars as the first genocide of the 20th century. Turkey denies that the deaths constituted genocide, says the toll has been inflated and insists that those killed were victims of civil war and unrest.

Just ahead of the vote, Turkey made a final direct appeal to U.S. lawmakers to reject the resolution. The U.S. vote comes as Turkey's government was seeking parliamentary approval for a cross-border military operation to chase separatist Kurdish rebels who operate from bases in northern Iraq. The move, opposed by the United States, could open a new war front in the most stable part of Iraq.

Shortly before Bush spoke against the resolution, Secretary of State Condoleezza Rice and Defense Secretary Robert Gates stood before microphones on the White House driveway to express the administration's worries.

Gates said that 70 percent of U.S. air cargo headed for Iraq goes through Turkey, as does about a third of the fuel used by the U.S. military in Iraq.

"Access to airfields and to the roads and so on in Turkey would very much be put at risk if this resolution passes and Turkey reacts as strongly as we believe they will," Gates said. He also said that 95 percent of the newly purchased Mine Resistant Ambush Protected vehicles are being flown through Turkey to get to Iraq.

The White House and Turkey are now expected to pressure Democratic leaders to keep the measure off the floor of the full House. But Democratic Speaker of the House Nancy Pelosi has signaled that they will have a hard sell.

Pelosi and the second-ranking Democrat in the House, Majority Leader Steny Hoyer, met Wednesday with Turkish Ambassador Nabi Sensoy but emerged from the meeting unswayed. Hoyer told reporters he expects a floor vote on the measure before the House adjourns for the year.