"It's very difficult without paid signature gatherers, but the ground swell is so great, it actually possible that we just might make it," Pacific Justice Institute spokesperson Brad Dacus said.
But a last-minute email plea to supporters says it would take a "miracle" to get the number of signatures required to qualify the referendum and that help is needed.
Gay rights groups are crossing their fingers, hoping the effort falls short. They've been working for years to get themselves included in textbooks.
"It's necessary because there's a whole community that has been censored out of our education system," Equality California spokesperson Mario Guerrero said.
What has hurt the referendum movement is the lack of big money that was behind Proposition 8, the controversial initiative that banned same sex marriage in California.
The repeal on Senate Bill 48 has mostly been a volunteer effort centered around concerns that schools will teach homosexuality. If it fails to meet the Wednesday deadline, the same groups may try for an initiative on the November 2012 ballot.
"When it comes to defending the rights of parents and protecting children, we at Pacific Justice Institute are willing to look at all avenues necessary to be able to do so," Dacus said.
Supporters of the inclusion of gay history say the new textbooks could help combat bullying and promote greater understanding. They don't want to wait and feel the new books are needed now.
"It would mean so much; had it been around when I was younger, it probably would have saved me from a lot of the trauma I had to go through," Javier Pinedo, who was bullied as a teen, said.
Since California is the largest textbook buyer in the country, publishers will try to sell the California edition to other states. So whatever happens has national implications.