President Obama is seen on a monitor in the White House briefing room as he tells an ABC interviewer that he supports same-sex marriage. (Carolyn Kaster/AP)

President Obama is heard endorsing same-sex marriage in a new radio ad being aired by supporters of Question 6, the Maryland ballot measure that would legalize gay unions.

The ad, which is airing in both the Washington and Baltimore markets, features a clip from Obama’s ABC News interview in May in which he talked about having “evolved” on the issue.

“Same-sex couples should be able to get married,” Obama says in the clip. “I had hesitated on gay marriage because I thought civil unions would be sufficient.”

The clip is played about half way through the 60-second spot, which is build around a dramatized discussion between two women about Question 6.

One woman tells the other she made up her mind on same-sex marriage after hearing Obama talk about it. She tells her friend that she kept the clip of his endorsement on her mobile phone because “it’s that important.”

The ad, produced by Marylanders for Marriage Equality, highlights the emphasis both sides have put on wooing African-American voters, who make up a larger share of the electorate in Maryland than in any state outside the Deep South.

A Washington Post poll released last week showed 42 percent of African American voters support Question 6, while 53 percent oppose it. Among white voters, 56 percent favor the measure, and 39 percent oppose it.

Opponents of Question 6 have networked for months through black churches.

The Maryland Marriage Aliance, the group leading the opposition, also has a new radio ad that features Alveda King, the niece of the slain civil rights leader, Dr. Martin Luther King, Jr.

“Gay and lesbian couples already have rights under Maryland law, like priority hospital visitation, sharing property, tax exemptions, adoption and the list goes on,” King says in the ad. “It is possible to be tolerant of gay and lesbian rights without redefining marriage, God’s holy union.”

Proponents have also featured civil rights leaders and black ministers in their ads, arguing that allowing gay people to wed is the fair thing to do whether one personally approves or not.

They have also emphasized Obama’s conversion and the endorsement of same-sex marriage this spring of the NAACP.

This story has been updated.