Maryland Gov. Martin O’Malley is set to sign a law legalizing same-sex marriage today at 5 p.m., kicking off a celebration for supporters of marriage equality and a petition-drive for its opponents.

The law will go into effect in January 2013, unless voters say otherwise in a November referendum opponents are hoping to organize. The Washington Times reports that same-sex marriage foes have said that they’re aiming to start circulating petitions next week to put the law to a popular vote in November. To do so, they’ll have to gather close to 56,000 signatures by the end of June. If it’s left to voters, the fate of same-sex marriage in Maryland would be too close to call—according to the Baltimore Sun, a recent poll put support at 49 percent and opposition at 47 percent, both within the margin of error.

Regardless of that possibility, WTOP reports that businesses in Maryland are looking forward to the boost the state could see if it becomes the ninth jurisdiction in the U.S. where same-sex marriage is legal (eight states and the District permit it). If D.C. is any example, though, Maryland businesses shouldn’t expect too much—according to The Washington Blade, the marriage equality business spike was lower than expected.