Foes of a California law which mandates schools teach about the historical contributions of gay, lesbian, bisexual and transgender people conceded on Monday that they have failed to qualify a ballot measure which would have repealed the law.

Senate Bill 48 (SB48) or the FAIR Education Act, sponsored by state Senator Mark Leno, a Democrat from San Francisco, took effect in January and requires that the California Board of Education and local school districts include the curriculum in their lesson plans.

Opponents of the law had until Monday to collect the signatures of 504,760 registered voters to qualify for the 2014 statewide ballot.

“While boxes of signed petitions are still being delivered to locations throughout the State, the coalition that promoted the Children Learning Accurate Social Science (CLASS) Act is projecting today that they will fall short of the more than 500,000 signatures needed to qualify the initiative for the 2014 ballot,” the Pacific Justice Institute said in an e-mail to supporters.

“Placing a measure on the ballot through grassroots efforts alone has not been done in California in recent memory. Although history was against us, our conscience compelled the coalition to fight this battle rather than doing nothing,” said Kevin Snider, chief counsel to Pacific Justice Institute.

An earlier attempt by the group to put the law to a popular vote also did not qualify.