ANNAPOLIS, Md. (CBSDC/AP) — Opponents of a measure that gives gay couples the right to marry in Maryland have officially begun their effort to overturn the law.

Maryland Marriage Alliance officials announced Wednesday that they have launched the petition drive to collect the nearly 56,000 signatures needed to bring the law to referendum on the November ballot.

The group, which is leading the referendum effort, is working with mdpetitions.com, an organization and website developed last year by a Maryland delegate, to collect signatures.

Voters can visit the website and request a petition form be mailed to them.

The website uses information from state voter rolls to ensure a signer’s printed name and address will match Maryland records, a standard used by the state Board of Elections to validate the signatures.

Gay marriage advocates have also launched their own petition to gather support for upholding the gay marriage law. People who sign it will be pledging their support for same-sex marriage according to organizers of petition.

That petition will not carry any legal weight.

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