BELLEVUE, Wash. (AP) – Log Cabin Republicans are taking aim at a proposed federal constitutional amendment to ban same-sex unions.

The state chapter of the country’s leading group of gay GOP activists began airing 30-second TV spots on cable channels in the Seattle market, opposing the amendment that President Bush and a number of GOP leaders have embraced.

The organization set up a display table at the state Republican Convention, airing the TV commercial and talking with delegates about the issue.

The convention was expected to approve a platform backing a constitutional amendment defining marriage as the union of a man and a woman. The platform plank also said, “We understand that a primary responsibility of government is to uphold and respect traditional institutions, such as marriage between a man and a woman, and family, which are its foundation.”

The proposed platform also said schools should not “promote or identify homosexuality as a healthy, morally acceptable or alternative lifestyle.”

The commercial, which cost $10,000 to air for three days, used a clip from Vice President Dick Cheney’s 2000 debate with his Democratic rival, Joe Lieberman. Although Cheney now backs the amendment, at the time he said, “That matter is regulated by the states. I think different states are likely to come to different conclusions and that’s appropriate. I don’t think there should necessarily be a federal policy in this area.”

Cheney has a lesbian daughter.

Dave Kaplan, 43, president of the state Log Cabin organization, said the group is running ads in political swing states that may be amenable to the argument that the issue of same-sex marriage should be kept out of the Constitution and handled by the states.

“As GOP leaders from across Washington state come together, this ad sends an important message – you can be a good and loyal Republican by opposing efforts to write discrimination into the Constitution,” said Brian Ballard, a national board member from Seattle.

“To be the majority party in this state and this country, the GOP must continue to embrace its core principles – limited government, low taxes, a strong defense, personal responsibility and individual freedom. Extremism will lead to defeat.”

Same-sex marriage is a complicated and emotional issue that society is just starting to discuss, Kaplan said in an interview.

“We just think that everyone should be treated the same under the law,” he said, adding that the party should “resist exclusion and discrimination.”

The organization, named to honor Abraham Lincoln and his support of equality, hasn’t decided whether to withhold its endorsement from the president. Bush has been inclusive in some ways and has appointed some openly gay people to his administration, Kaplan said.

The group said it received a mostly polite reception at the convention. At an earlier convention, some delegates surrounded gay rights activists and prayed for them.

State GOP Chairman Chris Vance welcomed the group, saying, “They are loyal Republicans who disagree with the majority of the party on this issue. Fine.”

Rick Forcier, a delegate from Thurston County who is state director of the Christian Coalition, said, “A substantial portion of the Republican grassroots supports traditional marriage, traditional family.”

He said support of the constitutional amendment was “just a given” and sailed through the platform committee without much discussion.