WASHINGTON (CNN) -- With tensions rising between the United States and Turkey over a resolution that labels the World War I-era massacre of Armenians by Turkish forces "genocide," many are asking why the House is debating the resolution now.

Rep. Tom Lantos says passage of the genocide resolution would help restore America's moral authority.

The House Foreign Affairs committee voted 27-21 Wednesday to approve the nonbinding resolution, which declares that the deportation of nearly 2 million Armenians from the Ottoman Empire between 1915 and 1923 -- resulting in the deaths of 1.5 million -- was "systematic" and "deliberate," amounting to "genocide."

The Democratic leadership has not scheduled a final vote.

Administration officials have lobbied against the resolution, saying good U.S-Turkish relations are vital to U.S. forces in Iraq. The Pentagon says 70 percent of the military's cargo heading into Iraq either flies into or over Turkey.

But House Democrats view the resolution as part of their mandate to restore America's moral authority around the world.

House Speaker Nancy Pelosi Thursday said arguments that Turkey is too vital an ally to alienate has delayed the resolution for too long. Watch Speaker Pelosi defend the timing of the debate »

"I've been in Congress for 20 years. And for 20 years, people have been saying the same thing." Pelosi said Thursday. "There's never a good time. And all of us in the Democratic leadership have supported... reiterating the Americans' acknowledgement of a genocide."

"As long as there is genocide, there is need to speak out against it," she added.

And one of the chief supporters of the resolution, House Foreign Affairs Chairman Tom Lantos, D-California, was unmoved by the administration's arguments that Turkey would block the use of U.S. airbases on Turkish soil.

"The Turkish government will not act against the United States because that would be against their own interests," he told CNN. "I'm convinced of this."

Lantos, the only member of the House who is a Holocaust survivor, says passage of the resolution would also help to bring a moral dimension back to U.S. foreign policy.

"One of the problems we have diplomatically globally is that we have lost our moral authority which we used to have in great abundance," Lantos said. "People around the globe who are familiar with these events will appreciate the fact that the United States is speaking out against a historic injustice. This would be like sweeping slavery under the rug and saying slavery never occurred."

But Democrats are not united behind the measure, Armed Services Committee Chairman Ike Skelton, D-Missouri, has sent a letter to Pelosi on Thursday opposing the resolution, saying the resulting backlash threatened by Turkey could disrupt "America's ability to redeploy U.S. military forces from Iraq," a top Democratic priority.

And the top Republican in the House, Minority Leader John Boehner, R-Ohio, said Thursday that bringing the resolution up for a final vote would be "totally irresponsible."

"The fact is that Turkey is a very good ally of the United States. They are critical to our security, not only her to but our troops oversees," Boehner said. "Let the historians decide what happened 90 years ago." E-mail to a friend

CNN's Dana Bash contributed to this report.

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