A third national poll shows a slim majority of Americans favor legalizing marriage for gay and lesbian couples.

The Washington Post-ABC News survey released Friday found 53 percent of Americans support gay marriage, while 42 percent remain opposed. That is a 17 point increase in support over the last five years.

“This newest poll confirms yet again that Americans have been on a journey of understanding, living up to the American value of treating others as we would all want to be treated and staying true to our nation's history of upholding the American promise of equality under the law,” Evan Wolfson, president of Freedom to Marry, said in a statement.

Wolfson added that “hearts have opened and minds have changed” as Americans “have had time to hear more about the lives and families of their gay and lesbian neighbors, co-workers and family members.”

Two previous national polls, one by the Associated Press and another by cabler CNN, also concluded that a narrow majority of Americans favor legalizing marriage for gay couples.

The National Organization for Marriage (NOM), the nation's most vociferous opponent of gay marriage, decried the poll as biased.

“The only poll that counts is a free and fair vote on the part of the people,” NOM President Brian Brown told the Post. “We've seen these biased polls time and time again – right before votes in which same-sex marriage is rejected. It's absurd. The people of this country have not changed their opinion about marriage.”

Brown, however, didn't mention his group's own very biased polling in Maryland. NOM's survey found a whopping 78 percent of Marylanders in favor of putting the issue up for a vote.

NOM's pollster, Lawrence Research, was heavily involved in the effort to get California's gay marriage ban, Proposition 8, approved. And company founder Gary Lawrence served as the grassroots director for the Yes on 8 campaign organized by The Church of Jesus Christ of Latter-day Saints, the Mormons. The church's members played a large financial and organizational role in getting Proposition 8 approved.