(12-08) 20:26 PST San Francisco -- Since California voters approved Proposition 8 last month and repealed the right of gay couples to marry, initiative opponents have marched, held rallies and blocked intersections.

On Wednesday, they're asked to do something different: nothing at all.

Modeled loosely after the 2006 immigrant rights demonstrations, "Day Without A Gay" is scheduled for Wednesday and billed as "a nationwide strike and economic boycott" at www.jointheimpact.com, an organizational site for supporters of same-sex marriage.

In San Francisco, the day will be marked by a 6 p.m. rally and march in the Mission District. But local organizers say they don't expect all Prop. 8 opponents to "call in gay" and instead spend the day doing volunteer work, as some proponents urge.

"I'd like to take the whole day off myself, but it's not possible," said Ryan Rudnick, a pre-school teacher who also helped organize a Nov. 15 rally outside City Hall that attracted an estimated 7,500 supporters of same-sex marriage. "That's why we wanted to hold a rally and march in the evening, to show our support."

Like many actions in the five weeks since Prop. 8's passage with 52.3 percent of the vote, "Day Without a Gay" took shape informally.

The name was coined by Sean Hetherington, a personal trainer and comedian in West Hollywood who added the idea of doing volunteer work, rather than pursuing civil disobedience or other tactics.

The web site Hetherington created for the event, www.daywithoutagay.org, also offers a list of activities for people who don't feel able to walk off their jobs.

"With the economy the way it is, this isn't a time for not showing up at work and then perhaps not having a job," said Hetherington, who will spend the day teaching joke-writing at a school in the Los Angeles area. "We want people to go in and make whatever opportunity they can."

The San Francisco event will begin with a 6 p.m. rally outside the BART station at 24th and Mission streets, followed by a march north on Valencia Street.

As for the broader call of boycotts, Prop. 8 opponents say success or failure can't be measured by numbers.

"It's organic, it's visceral, it's grass roots and net roots," said State Sen. Mark Leno, D-San Francisco, who spoke at the November rally at City Hall. "People are reacting in a very natural way to having their rights taken away by an unconstitutional proposition."

Leno's schedule Wednesday starts with a budget subcommittee on health and human service issues. "Though I'm respectful of the day," Leno said, legislative work comes first.