Fliers handed out today urging voters to uphold Maryland’s same-sex marriage law featured the endorsement of first lady Michelle Obama. (Photo via @LenoreGore)

The lone campaign worker standing outside a sleepy polling place on Georgia Avenue in downtown Silver Spring this afternoon was there to support an expansion of casino gambling across Maryland. Kevan McDonald, a Rockville resident, sat alone, handing out sky-blue fliers produced by Maryland Democrats backing the passage of seven ballot questions. Though he was most prepared to talk to voters about Question 7.

Surrounding McDonald, though, was a litter of yard signs planted in the mulched flowerbeds outside the polling place, many of which urged passage of Question 6, the measure that, if passed, will uphold Maryland’s same-sex marriage law passed in March.

Even though no one from Marylanders for Marriage Equality, one of the lead groups fighting to uphold the law, was outside the Georgia Avenue building, the group says it made a highly visible statewide effort today. Over 2,000 of the organization’s volunteers plastered polling places across the state, said Kevin Nix, Marylanders for Marriage Equality’s spokesman.

Just as in presidential bids, issue campaigns rely on an active ground game. Human Rights Campaign, a leading gay-rights group, also sent its people into the field today. High-profile backers also worked the polls today, with Gov. Martin O’Malley and Baltimore Ravens linebacker Brendon Ayanbadejo greeted voters at a school in Baltimore.

“Reception has been great,” Paul Guequierre, a spokesman for HRC said. Human Rights Campaign is also working to pass same-sex marriage initiatives in Maine and Washington today, and beat back a constitutional amendment in Minnesota that would bar same-sex couples from marrying.

Nix, though, remained as cautious on Election Day as he did yesterday.

“I think it’s going to be a close race but we have a close shot of pulling this out,” he said Monday.

There was no sign of opponents of same-sex marriage in Silver Spring, though opponents of the law O’Malley signed March 1 also campaigned around Maryland today, though to what effect is uncertain. The Maryland Marriage Alliance, a leading opponent of same-sex marriage, issued a call over Twitter for photos of rallies urging voters to defeat Question 6. There were no replies.

Polls in Maryland close at 8 p.m.