Proponents of upholding Maryland’s same-sex marriage law on Tuesday launched on a new Web video featuring a series of African-Americans explaining why they are supporting this fall’s referendum.

“As an African-American male, I know what it’s like to be discriminated against,” says LeVar Michael, one of the featured voices in the three-minute video produced by Marylanders for Marriage Equality.

African Americans are a key demographic for both sides in the fight over the November ballot measure. The percentage of black residents in Maryland is the largest outside the deep South, and polling has long shown their support for same-sex marriage, as a group, lags the population as a whole.

In the wake of President Obama’s announcement in May that he supports same-sex marriage, there has been evidence that some minds are changing, however, and proponents say they see an opportunity to build support among African Americans.

The Maryland Marriage Alliance, the lead group seeking to overturn the law, had no immediate comment Tuesday in response to the new Web ad.

With the ad, Marylanders for Marriage Equality are returning to a tactic employed in the weeks leading up to February’s passage of the same-sex marriage law by the Maryland General Assembly.

Those Web ads featured an array of voices — many of them politicians and celebrities — voicing their support for the legislation, which Gov. Martin O’Malley (D) proposed and signed into law in March.

The law, scheduled to take effect in January, will be put on hold pending a statewide vote, because opponents gathered enough signatures to place the issue on the ballot.