(San Francisco, California) The battle over a battle effort to amend the California Constitution to ban same-sex marriage could be the most costly amendment ever.

The latest contribution to LGBT groups fighting the proposed ban, called Proposition 8, is $100,000 from the Gay & Lesbian Alliance Against Defamation.  The money is in addition to in-kind services donated by the group to the campaign.

“GLAAD’s board of directors and staff are proud to play our part in this vital effort to ensure that all loving and committed couples in California continue to have the protections and the security that marriage provides,” said Dr. Yvette Burton, co-chair of the organizations National Board of Directors.

The contribution will go to support public education and voter outreach efforts in California. In addition, the organization is working with campaign coalition partners to provide staff support and resources for the campaign.

Ten days ago, California’s largest public utility gave a quarter-million dollars to the fight against a proposed constitutional amendment.

Pacific Gas and Electric Company turned the check over to NO on 8 – the organization formed by Equality California, the state’s largest LGBT civil rights group to fight the measure. The contribution is the largest corporate donation the group has received.

Neither side on the ballot measure has said exactly how much has been raised but it is believed to be in the millions.

Earlier this week the Knights of Columbus donated $1 million to Protect Marriage the group behind the ballot measure. The money is in addition to the $250,000 the Catholic group already had donated.

Among other major donors to Protect Marriage are a group of San Diego County businessmen. 

Developer Doug Manchester alone has contributed $125,000, prompting gays to urge a boycott of his properties.  Manchester owns the Manchester Grand Hyatt and the San Diego Marriott Hotel and Marina.

Mission Valley developer Terry Caster has donated $162,500, Carlsbad car dealer Robert Hoehn gave $25,000, and La Jolla businessman Roger Benson has given $50,000, according to state records.

Earlier this month a state appeals court in Sacramento turned down an urgent appeal of a lower court ruling that upheld Attorney General Jerry Brown’s definition of the proposed constitutional amendment.

Protect Marriage had alleged that Brown’s wording for the ballot of the measure was prejudicial.

The ballot question originally had been described as a measure to limit marriage between a man and a woman. Last month, Brown changed the description to say the proposed amendment would eliminate the right of same sex couples to marry and that it could result in California losing tens of millions of dollars in taxes.

Brown, a Democrat, opposes the amendment. Gov. Arnold Schwarzenegger (R) oalso pposes the amendment and has said he will campaign against it.

A poll released in July suggests the measure is likely to be defeated.

Fifty-one percent of likely voters said they would vote against the proposed amendment while 42-percent would support it.