Producer Steve Bing plans to contribute $500,000 to the campaign to defeat a proposed constitutional ban on same-sex marriage in California.

Bing’s contribution, the largest so far from an entertainment industry figure to the No on 8 campaign, will be made in its entirety if it is matched by other donors, said Chad Griffin, a political strategist for the campaign who also works with Bing on political and environmental issues. Bing’s contribution also is the largest coming from a non-LGBT individual to the campaign.

In recent weeks, fund-raising for No on 8 has picked up, and backers are planning a fund-raiser on Tuesday at the Beverly Hills home of Ron Burkle, with Mary J. Blige and Melissa Etheridge providing entertainment.

“This measure impacts clients, co-workers, employees, friends and family of just about everyone in the industry, so I am hopeful industry leaders will respond,” Griffin said. “This is not just another ballot measure. It is unique in that it eliminates fundamental rights in a way that deeply affects people’s lives.”

No on 8 campaign manager Patrick Guerriero said in a conference call on Wednesday that recently, “We’ve seen an amazing mobilization of people who realize what is at stake here.”

Alarm bells have been sounded in recent weeks after polls showed Yes on 8 gaining ground and even winning, and holding a big advantage in fund-raising. In the Wednesday call, Guerriero pointed out that some 40% of the contributions to Yes on 8 have come from members of the Mormon Church.

What created a stir last month was an article in IN Los Angeles magazine that listed a number of prominent gay industry figures who had yet to give to the No on 8 campaign, perhaps a function of the attention the presidential race has taken from other causes. Some, like Gus Van Sant and Greg Berlanti, have given since, according to state fund-raising records.

Noting the lag in contributions coming from the entertainment industry, entrepreneur Jonathan Lewis gave $500,000 to the No on 8 campaign on the condition that it be matched. Organizers say they have recently reached that threshold.

Other prominent figures have yet to give, although some of their reps point out that they are making contributions in other, perhaps even more effective ways. In addition to releasing photos of her marriage to Portia de Rossi, Ellen DeGeneres recently posted a Web video for No on 8 on her talkshow’s website, and has talked about a marriage ban on her show and on “The Tonight Show With Jay Leno.”

Bing is one of the nation’s most prolific donors to Democratic and progressive causes. He’s the top individual contributor to the 527 independent committees this cycle, having contributed more than $4.8 million, according to the Center for Responsive Politics. In 2006, he contributed about $50 million to a California alternative energy initiative, one that fell short at the ballot box as oil and energy companies spent about double that amount to defeat it.

Sonja Eddings Brown, a spokeswoman for Yes on 8, disputed Guerriero’s contention that 40% of the Protect Marriage support is coming from the Mormon community and said that the source for that figure, Mormons for 8, was “not even a credible Website.” Rather, she noted, their contributions were coming from a cross section of faith groups. She noted that their campaign had drawn some 62,000 donors.

“Our campaign we really feel is from the people, and it is because this issue affects every home and every family, and because it affects the civil rights of children,” she said.