Maryland's State Senate approved a same sex marriage bill last night that would make it the eighth state where gay and lesbian couples can marry. Governor Martin O’Malley has promised to sign the bill into law, but the fight is just beginning, as voters will be given a chance to weigh in before any marriages actually take place.

As part of the conditions agreed to in order to get the bill passed through the House, opponents of the new law will be given an opportunity to put the issue on the ballot in November, raising the possibility of a major public fight this summer and fall. The law will also not go into effect until all legal challenges have been exhausted, which could be a matter of years. 

The state's close proximity to Washington, DC, could also shove the issue into the presidential campaign. President Obama had probably hoped to avoid talking about gay marriage until after re-election, but the increasing focus on social issues during the campaign, combined with more and more states taking up the fight, may make it unavoidable. Just two weeks ago, Washington State approved a similar measure to join Connecticut, Iowa, Massachusetts, New Hampshire, New York and Vermont as the states where same sex marriage is legal. New Jersey's legislature passed a bill last week that was vetoed by Governor Chris Christie; Minnesota and North Carolina will vote on proposals to ban gay marriage this November; and California's own ballot initiative was struck down by appeals courts earlier this month.

Obama has managed to avoid stepping on the issue so far, but the Maryland bill may force his hand. He has refused to endorse gay marriage officially, but his administration has also failed to defend the Defense of Marriage Act in court — which was just ruled unconstitutional by a federal judge — and has not come out explicitly against any of the laws passed since he became president. With the fight in his backyard being led in part by African-American church leaders opposed to this bill, he will likely face pressure from both sides to take a more definitive stand later this year.